Detection of a plunger position in an irrigation control device

ABSTRACT

Some embodiments provide irrigation valve control apparatuses comprising: a solenoid configured to cooperate with a plunger; an input stimulus source coupled with the solenoid and configured to apply an input stimulus while a plunger drive signal is not being applied and that is sufficiently small to not cause the plunger to move; sampling circuitry configured to measure one or more voltage measurements corresponding to one or more voltages across the solenoid, wherein the one or more voltage measurements are dependent upon the current position of the plunger relative to the solenoid; and control circuitry cooperated with the sampling circuitry to receive the one or more voltage measurements from the sampling circuitry, wherein the control circuitry is configured to determine whether the plunger is in one of the open and closed positions based on the one or more voltage measurements.

This application is a continuation of U.S. application Ser. No.15/945,614, filed Apr. 4, 2018, entitled DETECTION OF A PLUNGER POSITIONIN AN IRRIGATION CONTROL DEVICE (Attorney Docket No. 8473-142813-US),which is a continuation of U.S. application Ser. No. 15/445,390, filedFeb. 28, 2017, entitled DETECTION OF A PLUNGER POSITION IN AN IRRIGATIONCONTROL DEVICE (Attorney Docket No. 8473-140465-US), now U.S. Pat. No.9,964,231, which is a continuation of U.S. application Ser. No.14/133,595, filed Dec. 18, 2013, entitled DETECTION OF A PLUNGERPOSITION IN AN IRRIGATION CONTROL DEVICE (Attorney Docket No.8473-131767-US), now U.S. Pat. No. 9,618,137. All of these applicationsare incorporated by reference in their entirety herein.

This application is related to U.S. patent application Ser. No.14/133,598 (entitled “VOLTAGE COMPENSATION IN AN IRRIGATION CONTROLDEVICE”, Attorney Docket No. 8473-132128-US), which is incorporated byreference in its entirety herein.

BACKGROUND 1. Field of the Invention

The present invention relates generally to irrigation, and morespecifically to apparatus and methods of controlling and implementingirrigation.

2. Discussion of the Related Art

Typical irrigation control systems cooperate with water valves and pumpsto control the flow of irrigation water through a variety of waterdispensing devices, including sprinklers, rotors, drip-lines, and otherwater delivery devices. These control systems are used in a wide varietyof irrigation applications, from residential and commercial landscapesto golf course and agricultural irrigation.

Many irrigation systems and electronics are powered by 50/60 Hz ACvoltage signals. Some systems further modulate this power source toprovide data communication, for example, by selectively clipping thepositive half of a cycle of the AC voltage signal. Data and power sentin this manner are often over a two-wire transmission line and are oftenreferred to as a two-wire interface. Irrigation devices variouslylocated in the field couple to the two-wire interface and derive theiroperational power therefrom. Some irrigation devices can demodulate thedata by monitoring the received power signal. These irrigation devicescan control water flow through valves based on received signaling, forexample, by actuating one or more solenoid control valves.

SUMMARY OF THE INVENTION

Some embodiments provide irrigation valve control apparatusescomprising: a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal from plunger activation circuitry whereinthe plunger drive signal is configured to induce a magnetic fieldrelative to the solenoid that causes the plunger to change positionsbetween open and closed positions; an input stimulus source coupled withthe solenoid and configured to apply an input stimulus into the solenoidat a time while the plunger drive signal is not being applied to thesolenoid, wherein the input stimulus is sufficiently small that theinput stimulus applied to the solenoid does not cause the plunger tomove from a current position; sampling circuitry configured to measureone or more voltage measurements corresponding to one or more voltagesacross the solenoid, wherein the one or more voltage measurements aredependent upon the current position of the plunger relative to thesolenoid in response to applying the input stimulus to the solenoid; andcontrol circuitry cooperated with the sampling circuitry to receive theone or more voltage measurements from the sampling circuitry, whereinthe control circuitry is configured to determine whether the plunger isin one of the open and closed positions based on the one or more voltagemeasurements.

Other embodiments provide irrigation apparatuses comprising: a solenoidconfigured to cooperate with a plunger and to receive a plunger drivesignal from plunger activation circuitry wherein the plunger drivesignal is configured to induce a magnetic field relative to the solenoidthat causes the plunger to change positions between open and closedpositions causing an opening and closing of an irrigation valve; firstswitching circuitry cooperated with the solenoid, wherein the firstswitching circuitry is configured, upon activation, to dictate adirection of electrical current flow through the solenoid, wherein thedirection of current flow while the plunger drive signal is appliedcontrols a direction of movement of the plunger in response to theapplication of the plunger drive signal; an input stimulus sourcecooperated with the solenoid, wherein the input stimulus source isconfigured to generate an input stimulus that is applied to a firstterminal of the solenoid at a time while the plunger drive signal is notbeing applied to the solenoid, and wherein the input stimulus does notcause the plunger to change from a current position; a resistive loadcooperated with a second terminal of the solenoid; sampling circuitrycoupled with the resistive load, wherein the sampling circuitry isconfigured to measure one or more voltage measurements across theresistive load in response to the input stimulus; and control circuitrycoupled with the sampling circuitry, wherein the control circuitry isconfigured to receive the one or more voltage measurements, determine acurrent passing through the resistive load as a function of the one ormore voltage measurements, determine an inductance of the solenoid as afunction of the determined current and a timing of the input stimulus,and determine whether the plunger is in one of the open and closedpositions as a function of the determined inductance of the solenoid.

Additionally, some embodiments provide irrigation valve controlapparatuses comprising: a solenoid configured to cooperate with aplunger and to receive a plunger drive signal from plunger activationcircuitry wherein the plunger drive signal is configured to induce amagnetic field relative to the solenoid that causes the plunger tochange positions between open and closed positions resulting in openingor closing a valve such that water is allowed to pass through the valvewhen the plunger is in the open position and water is prevented frompassing the valve when the plunger is in the closed position; controlcircuitry cooperated with the solenoid and configured to direct theplunger drive signal into the solenoid to induce movement of theplunger; an input stimulus source cooperated with the solenoid andconfigured to apply an input stimulus into the solenoid at a time whilethe plunger drive signal is not being applied to the solenoid, whereinthe input stimulus that is sufficiently small that the input stimulusdoes not cause the plunger to move from a current position; and aresonant circuit comprising the solenoid, wherein the resonant circuitis coupled with the input stimulus source and configured to be excitedby the input stimulus to generate a resonant response that resonateswhen the plunger is in one of the open position and the closedpositions; wherein the control circuitry is configured to determinewhether the resonant response is generated in response to the inputstimulus, and to determine whether the plunger is in one of the open andclosed positions in response to whether the resonant response isgenerated.

In some embodiments, methods of controlling an irrigation device areprovided. These methods can comprise: causing an input stimulus to beapplied to a solenoid at a time while a plunger drive signal is notbeing applied to the solenoid, wherein the solenoid is configured tocooperate with a plunger and to receive the plunger drive signal thatinduces a magnetic field relative to the solenoid that causes theplunger to change positions between open and closed positions, andwherein the input stimulus does not cause the plunger to change aposition; taking one or more voltage measurements across the solenoid inresponse to the input stimulus being applied to the solenoid, whereinthe voltage of the one or more voltage measurements are dependent uponthe position of the plunger relative to the solenoid in response to theinput stimulus applied to the solenoid; evaluating the one or morevoltage measurements; and determining whether the plunger is in one ofthe open and closed positions based on the one or more voltagemeasurements.

Further, some embodiments provide methods of controlling an irrigationdevice, comprising: causing an input stimulus to be generated andapplied to a first terminal of a solenoid, wherein the solenoid iscooperated with a plunger that is configured to be movable between openand closed positions in response to a magnetic field generated by thesolenoid in response to a plunger drive signal causing an opening andclosing of an irrigation valve, and wherein the input stimulus does notcause the plunger to change positions and the input stimulus is appliedto the solenoid while the plunger drive signal is not being applied tothe solenoid; causing one or more voltage measurements to be takenacross a resistive load cooperated with a second terminal of thesolenoid in response to the input stimulus; determining a currentthrough the resistive load as a function of the one or more voltagemeasurements; determining an inductance of the solenoid as a function ofthe determined current and a timing of the input stimulus; evaluatingthe determined inductance relative to a first inductance threshold; anddetermining whether the plunger is in one of the open and closedpositions as a function of a first relationship between the determinedinductance of the solenoid and the first inductance threshold.

Still further, some embodiments provide methods of controlling anirrigation device, comprising: injecting an input stimulus into aresonant circuit comprising a solenoid, wherein the solenoid isconfigured to cooperate with a plunger and to receive a plunger drivesignal from plunger activation circuitry wherein the plunger drivesignal configured to induce a magnetic field relative to the solenoidthat causes the plunger to change positions between open and closedpositions resulting in opening or closing a valve such that water isallowed to pass through the valve when the plunger is in the openposition and water is prevented from passing the valve when the plungeris in the closed position, and wherein the input stimulus will not causethe plunger to move from a current position and the input stimulus isinjected while the plunger drive signal is not being applied to thesolenoid; wherein the resonant circuit is configured to be excited bythe input stimulus to generate a resonant response that resonates whenthe plunger is in one of the open position and the closed positions;determining whether the resonant response is generated in response tothe input stimulus; and determining, through control circuitry, whetherthe plunger is in one of the open position and closed positions inresponse to whether the resonant response is generated.

Some embodiments provide irrigation valve control apparatusescomprising: multiple terminals coupled with a multi-wire path; a firstcharge storage circuitry electrically coupled with at least one of themultiple terminals, wherein the first charge storage circuitry isconfigured to be charged by a voltage on the multi-wire path; a controlcircuitry configured to determine the voltage on the multi-wire path;and a boost circuitry controlled by the control circuitry, wherein thecontrol circuitry in response to determining that the voltage on themulti-wire path is below a threshold activates the boost circuitry toincrease a voltage stored by the first charge storage circuitry.

Furthermore, some embodiments provide methods of controlling irrigationvalves comprising: determining, at an irrigation valve controlcircuitry, whether a voltage on a multi-wire path is less than a firstthreshold, wherein the irrigation valve control circuitry is coupledwith the multi-wire path obtains power from the multi-wire path to openand close an irrigation valve; activating a boost circuitry in responseto determining that the voltage on the multi-wire path is less than thefirst threshold; generating a boost voltage, through the boostcircuitry, that is greater than the voltage on the multi-wire path whenthe voltage on the multi-wire path is less than the first threshold;charging, through the boost voltage, a first charge storage circuitry toa first voltage that is greater than the voltage on the multi-wire pathin response to the boost voltage; and discharging the first chargestorage circuitry to drive a current through a solenoid controllingmovement of a plunger to change positions to one of the open and closedposition, wherein moving the plunger controls the irrigation valve suchthat water is allowed to pass through the valve when the plunger is inan open position and water is prevented from passing the valve when theplunger is in a closed position.

Further, some embodiments provide an irrigation control apparatuscomprising: charge storage circuitry electrically coupled with amulti-wire path, wherein the charge storage circuitry is configured tobe charged by a voltage on the multi-wire path; boost circuitry coupledto the charge storage circuitry and configured to increase a voltagestored by the charge storage circuitry when the voltage on themulti-wire path is below a threshold; a solenoid configured to cooperatewith a plunger and to receive a plunger drive signal produced through adischarge of at least the charge storage circuitry; and plunger positiondetection circuitry configured to determine whether the plunger is inone of an open position and a closed position.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of severalembodiments of the present invention will be more apparent from thefollowing more particular description thereof, presented in conjunctionwith the following drawings.

FIG. 1 illustrates a simplified block diagram of an exemplary irrigationsystem, in accordance with some embodiments.

FIG. 2 depicts a simplified block diagram of an exemplary valveactivation system and/or integrated control module (ICM), in accordancewith some embodiments.

FIG. 3 shows a cross-sectional view of a simplified exemplary ICM, inaccordance with some embodiments.

FIG. 4 shows a simplified block diagram of exemplary circuitry or asystem comprising a plunger position detection circuitry (PPDC), inaccordance with some embodiments.

FIG. 5 depicts a representative simplified schematic diagram ofinductance-resistance-capacitance (LRC) circuitry, in accordance withsome embodiments.

FIG. 6 shows a simplified flow diagram of an exemplary process ofdetermining a location of a plunger that opens and closes a valverelative to a solenoid, in accordance with some embodiments.

FIG. 7 illustrates a simplified block diagram of an exemplary circuitryor system comprising a PPDC, in accordance with some embodiments.

FIG. 8A shows a circuit diagram of exemplary circuitry or a systemcomprising a PPDC, in accordance with some embodiments.

FIG. 8B show a circuit schematic of exemplary circuitry or systemcomprising a PPDC, in accordance with some embodiments.

FIG. 9 shows a graphical representation of the resulting voltage overtime as seen across a solenoid in response to an input stimulus when theplunger is in the open and closed positions, in accordance with someimplementations.

FIG. 10 shows a graphical representation of a corresponding voltage overtime across the solenoid in response to the input stimulus when aplunger is in the closed and open positions, in accordance with someembodiments.

FIG. 11 shows a simplified flow diagram of an exemplary process toidentify a location of the plunger based on a resonant response to theinput stimulus, in accordance with some embodiments.

FIG. 12 depicts a simplified block diagram representation of exemplarycircuitry forming at least part of a PPDC, in accordance with someembodiments.

FIG. 13 shows a circuit diagram of exemplary circuitry or a systemcomprising a PPDC, in accordance with some embodiments.

FIG. 14 shows a graphical representation of voltage measurements takenacross the resistance circuitry in response to a pulse input stimulusapplied to the solenoid, in accordance with some embodiments.

FIG. 15 shows a graphical representation of a corresponding currentthrough the solenoid when the plunger is in the closed and openpositions.

FIG. 16 illustrates graphical representations of current passing througha solenoid in response to a pulse input stimulus.

FIG. 17 shows graphical representations of voltage measured across aresistance circuitry at a time after the pulse input stimulus isinitially applied to a solenoid.

FIG. 18 shows a simplified flow diagram of an exemplary process, inaccordance with some embodiments, of determining a location of a plungerrelative to a solenoid based on an estimated inductance determined froma measured voltage.

FIG. 19 illustrates a simplified flow diagram of an exemplary process ofconfirming a location of the plunger and/or determining whether theplunger is stuck or otherwise malfunctioning, in accordance with someembodiments.

FIG. 20 illustrates a simplified block diagram of exemplary boostcircuitry, in accordance with some embodiments.

FIG. 21 shows a simplified flow diagram of an exemplary process, inaccordance with some embodiments, of boosting the voltage from themulti-wire path.

FIG. 22 depicts a simplified circuit diagram of exemplary boostcircuitry, in accordance with some embodiments.

FIG. 23 shows a graphical representation of a switch control signalapplied to switching circuitry of boost circuitry, in accordance withsome embodiments.

FIG. 24 illustrates a graphical representation of a change in currentthrough one or more power inductors in response to an activation ofswitching circuitry induced by a switch control signal, in accordancewith some embodiments.

FIG. 25 shows exemplary graphical representations of voltagemeasurements across the solenoid (vertical axis in A/D converter counts)relative to temperature (horizontal axis in Celsius), in accordance withsome embodiments.

FIG. 26 illustrates circuitry for use in implementing methods,techniques, devices, apparatuses, systems, servers, sources and the likein providing user interactive virtual environments in accordance withsome embodiments.

Corresponding reference characters indicate corresponding componentsthroughout the several views of the drawings. Skilled artisans willappreciate that elements in the figures are illustrated for simplicityand clarity and have not necessarily been drawn to scale. For example,the dimensions of some of the elements in the figures may be exaggeratedrelative to other elements to help to improve understanding of variousembodiments of the present invention. Also, common but well-understoodelements that are useful or necessary in a commercially feasibleembodiment are often not depicted in order to facilitate a lessobstructed view of these various embodiments of the present invention.

DETAILED DESCRIPTION

The following description is not to be taken in a limiting sense, but ismade merely for the purpose of describing the general principles ofexemplary embodiments. The scope of the invention should be determinedwith reference to the claims.

Reference throughout this specification to “one embodiment,” “anembodiment,” “some embodiments,” “some implementations” or similarlanguage means that a particular feature, structure, or characteristicdescribed in connection with the embodiment is included in at least oneembodiment of the present invention. Thus, appearances of the phrases“in one embodiment,” “in an embodiment,” “in some embodiments,” andsimilar language throughout this specification may, but do notnecessarily, all refer to the same embodiment.

Furthermore, the described features, structures, or characteristics ofthe invention may be combined in any suitable manner in one or moreembodiments. In the following description, numerous specific details areprovided, such as examples of programming, software modules, userselections, network transactions, database queries, database structures,hardware modules, hardware circuits, hardware chips, etc., to provide athorough understanding of embodiments of the invention. One skilled inthe relevant art will recognize, however, that the invention can bepracticed without one or more of the specific details, or with othermethods, components, materials, and so forth. In other instances,well-known structures, materials, or operations are not shown ordescribed in detail to avoid obscuring aspects of the invention.

Many irrigation systems include widely distributed irrigation valves,master valves, pumps and other such devices that are controlled throughone or more local irrigation controllers (sometimes referred to assatellite irrigation controllers) located at the site to be irrigatedand/or controlled through a central controller that can be local to thesite being irrigated and/or remote from the site being irrigated (e.g.,in wired and/or wireless communication with one or more local irrigationcontrollers through the Internet). In many of these irrigation systems,the irrigation valves are remote from the irrigation controllers thatoften provide power to the irrigation valves to open or close thevalves.

FIG. 1 illustrates a simplified block diagram of an exemplary irrigationsystem 100, in accordance with some embodiments. The irrigation systemincludes one or more Integrated Control Interfaces (ICI) 104 and/orother such control signal source, one or more wired or multi-wire paths106 (which are typically multi-wire paths comprising two or more wires),and one or more valve control circuitry, valve control apparatus, and/orintegrated control modules (ICM) 108 coupled with the multi-wire path106. The below is described with reference to ICMs; however, thoseskilled in the art will appreciate that the above and below descriptionwith reference to the ICM can readily apply to substantially anyrelevant apparatus, system, device or the like that controls one or morevalves or other such device, including systems having control circuitryseparate from a solenoid and/or solenoid assembly that causes movementof a plunger of a valve. The ICMs 108 cooperate with one or more valves110 or irrigation devices that include valves (e.g., rotors, sprinklersor the like with integrated valves) to control the valves.

In some embodiments, the irrigation system 100 optionally includes acentral controller or control computer 102 that is configured to couplewith the ICI 104 and/or other irrigation controller 112. Someembodiments additionally include one or more local irrigation controller(sometimes referred to as a satellite controller) 112. In someimplementations, the irrigation controller 112 couples with the centralcontroller 102, while in other embodiments the irrigation controller isa stand-alone irrigation controller that is configured to issue controlsover the multi-wire path 106. Still other embodiments do not include theICI 104, and instead include an irrigation controller 112 that may ormay not be coupled with the central controller 102. In some embodiments,the ICI 104 and/or irrigation controller 112 may be in communication,via direct connection or over a distributed network (e.g., intranet,LAN, WAN, Internet, etc.), with the central controller 102, which may belocated at the site where irrigation is implemented and/or remote fromthe site (e.g., a remote computer, a remote server operated over theInternet, a distributed server implemented through multiple devicesdistributed over the Internet and accessible by one or more users, theICI, a satellite irrigation controller, user device (e.g., usercomputer, smart phone, tablet, etc.), and/or other such systems that canprovide the central control). The below description generally refers tothe ICI 104 in communication with the ICMs 108; however, it will beappreciated that the irrigation controller 112 can additionally oralternatively be in communication with the ICMs and provide similarcontrol signals to the ICMs as dictated by an irrigation schedule beingimplemented by the central controller 102 or the irrigation controller.

The ICI 104 couples with the one or more ICM 108 over one or more wiredor multi-wire paths 106, where the wire paths comprise one or more wiresand typically include at least two wires. In some embodiments, amulti-wire path 106 may include three or more wires. Similarly, morethan one multi-wire path 106 can couple with the ICI 104 allowingadditional ICMs 108 to couple with the ICI and be controlled at least inpart through the central controller 102. The ICMs cooperate with one ormore valves 110 to control the valves. In some embodiments, the centralcontroller 102 in implementing irrigation issues commands in accordancewith one or more irrigation schedules to the ICI (or forwards theirrigation schedules to the ICI or irrigation controller 112). The ICI104 generates a modulated AC power signal that is transmitted over amulti-wire path 106. The ICMs 108 are coupled at various locations alongthe length of the multi-wire path 106. Further, the ICMs 108 arecooperated with the one or more valves 110, which are coupled with awater source (e.g., valve on a water conduit). In some implementations,the valves 110 are in a head sprinkler (e.g., rotor) or other waterdistribution device. The ICMs 108 receive operational power from the ACsignal applied over the multi-wire path 106. In some embodiments, theICI 104 modulates this AC signal to transmit data (such as turn on andoff commands) to one or more selected ICMs 108. The ICMs demodulate themodulated AC signal to determine whether the instructions apply to thatICM or to another one or more of the ICMs.

Further, in some embodiments, the ICI 104 (or irrigation controller 112)is configured to communicate, via wired or wireless communication, withother ICMs (e.g., wireless ICMs 116) that are also coupled with one ormore valves 110, which are coupled with a water source (e.g., valve on awater conduit) and/or are in a head sprinkler (e.g., rotor) or otherwater distribution device. These wireless ICMs 116 receive power from alocal source (e.g., battery power, solar power, etc.) or alternate ACpower source other than the multi-wire path 106 or a separate multi-wirepath.

The ICMs 108, 116 implement irrigation schedules and/or commandsreceived from the ICI 104 and/or locally defined (e.g., through aninterface or portable device in communication with the ICM, etc.). Insome embodiments, the ICMs 108 in opening or closing the valve 110control a solenoid, often a latching solenoid, that induces movement ofan internal plunger between open and closed positions. The movement ofthe plunger opens and closes the corresponding valve. For example, insome embodiments water is allowed to pass through the valve when theplunger is in the open position and water is prevented from passing thevalve when the plunger is in the closed position. In some embodiments,the ICMs 108 coupled with the multi-wire path can communicate back tothe ICI 104 over the multi-wire path, for example, by selectivelyshorting their connection to the multi-wire path 106 in a pattern, andoften at their assigned time. This results in a pattern of current drawsthat are detectable by the ICI 104 and can communicate the informationto the central controller 102, which results in the communication ofdata upstream to the ICI 104 and/or central controller 102.

By using the multi-wire path 106 the valves 110 can be widelydistributed over a relatively large area. For example, in someembodiments, the multi-wire path 106 may extend over several thousandfeet or more, and in some instances may include one or more branches.With such long lengths, numerous valves 110 and ICMs 108 can bedistributed along the multi-wire path. It can be very time consuming toverify the accurate operation of the ICMs and the valves.

Some embodiments provide the capability to determine whether a plungerof the valve is in a closed position, an open position, an undeterminedposition, removed from the solenoid and/or other information about theplunger and/or valve. Further, some embodiments provide sufficientprecision to identify substantially any position of the plunger. TheICMs 108, 116 can evaluate the plunger position and report the plungerposition back to the ICI 104 (irrigation controller 112) and/or thecentral controller 102. As such, these embodiments provide informationabout the operation of the valves 110 and/or whether there are errorsoccurring, which can result in damage to the plant life being irrigated,result in unnecessary costs, and/or waste resources. As described above,ICMs 108 coupled with the multi-wire path 106 are typically configuredto communicate with the ICI 104, an irrigation controller 112 and/or thecentral controller 102 via the multi-wire path (e.g., by shorting themulti-wire path). Similarly, ICMs 116 that wirelessly communicate canwirelessly communicate plunger position information to the ICI 104,irrigation controller 112 and/or the central controller 102.

FIG. 2 depicts a simplified block diagram of an exemplary ICM 108, 116,in accordance with some embodiments. The ICM includes front-end andcommunication circuitry 210, power distribution circuitry 212, acontroller and/or control circuitry 214, power control and switchingcircuitry 216, plunger position detection circuitry (PPDC) or system218, and a solenoid sub-assembly or circuitry 220. In some embodiments,the ICM 108 may optionally include voltage boost circuitry 222. Stillfurther, some embodiments may optionally include or couple withtemperature sensing circuitry and/or sensor(s) 224. The controller 214provides control over the ICM, including controlling the valve throughthe solenoid circuitry 220. In some embodiments, the controller 214comprises an integrated circuit (or circuits) that is configured and/orprogrammed to monitor and manage the functions in the operation of theICM. Again, the ICM includes and/or couples with a solenoid that movesan internal plunger between open and closed positions in response to amagnetic field generated through the solenoid depending on the directionof current passed through the solenoid.

Although FIG. 2 shows the various circuitry and/or components asdiscrete circuitry, two or more of these circuitry and/or portions oftwo or more of these circuitry may be cooperated into a single device,module, circuitry and/or system. For example, portions of the powercontrol and switching circuitry and the PPDC may be incorporated and/orimplemented through the controller 214. Similarly, some of the circuitryand/or components can be external to the ICM and operated in cooperationwith the ICM. For example, the boost circuitry could operate external tothe ICM and supply a boost voltage or signal as described below.Similarly, the controller 214 may be separate from the plunger positiondetection circuitry 218 and/or external to ICM. Further, in someembodiments, the control and/or electronic circuitry may be separatefrom one or more solenoid circuitry 220 and/or separate from one or moresolenoids that are configured to cooperate with a plunger of a valve. Insome implementations, some or all of the circuitry is integrated withthe solenoid circuitry, while in other instances the solenoid and/orsolenoid circuitry are implemented separate. For example, see U.S.application Ser. No. 12/510,111, filed Jul. 27, 2009, for InventorsCrist et al. (published as U.S. Pub. No. 2010/0082169), which isincorporated herein by reference, and which describes integrated andseparate circuitry. Additionally, some embodiments may include the boostcircuitry 222 while not including the PPDC 218, while other embodimentsmay include the PPDC 218 and not the boost circuitry 222. Otherembodiments, however, include both the boost circuitry 222 and the PPDC218.

FIG. 3 shows a cross-sectional view of a simplified exemplary ICM, inaccordance with some embodiments. The ICM 108 includes a solenoid 310, aplunger 312, and one or more circuit boards 314 that includes at leastsome of the circuitry 316 of the controller 214, which are positioned atleast partially within a housing 320 of the ICM. The circuit board 314and/or circuitry 316 typically implement the controller 214, PPDC 218,and/or other circuitry. The PPDC 218 and controller 214 use the solenoid310 to indirectly detect the position of the plunger 312.

Referring to FIGS. 1-3, the controller 214 in cooperation with the powercontrol and switching circuitry 216 induces movement of the plunger 312between the open to close positions. In some embodiments, the solenoid310 is configured to cooperate with the plunger 312 and to receive aplunger drive signal from a plunger activation circuitry of the powercontrol and switching circuitry. The plunger drive signal is configuredto induce a magnetic field relative to the solenoid 310, typicallydependent on a direction of current flow through the solenoid, thatcauses the plunger to move along an axis 318 and over a range of motionto change positions between open and closed positions. The plunger 312,in some embodiments, reciprocates relative to the solenoid. An end ofthe plunger may include a seal member and/or may couple with a portionof a valve that includes a seal member that closes or covers and opensor uncovers an opening or orifice of the valve 110.

In some embodiments, the switching circuitry 216 comprises one or moresolid state switches that selectively and directionally apply theplunger drive signal to the solenoid 310. The controller 214 and/or apower supply controller in communication with the controller 214determines an intended state of the valve (e.g., open or closed), andtypically based on the irrigation schedule. Further, the controller 214controls the switching circuitry 216 regarding the direction of currentflow through the solenoid as well as the timing of when the plungerdrive signal is applied to the solenoid and the relative duration of theplunger drive signal.

In some embodiments, the front-end and communication circuitry 210comprises terminals that couple with the multi-wire path 106 andreceives the modulated signals and the power from the multi-wire path.In some embodiments, the front-end and communication circuitry includesan AC to DC converter and a transceiver that includes or couples withone or more demodulators and a shorting circuitry to selectively shortthe connection of the ICM to the multi-wire path 106 in a pattern tocommunicate back up to the ICI 104 and/or central controller 102. Forexample, in some embodiments the front-end and communication circuitry210 serve as the interface between the ICM and the ICI 104 (and/orirrigation controller 112), accepts and rectifies the alternate current(AC) signal (e.g., about 26.5 VRMS, at about 50 Hz, 60 Hz, etc.), andprovides bidirectional communication between the ICM and the ICI.

The power distribution circuitry 212 cooperates with the front-endcommunication circuitry to draw power from the multi-wire path to powerthe ICM. In some instances, the power distribution circuitry 212 drawspower at a desired voltage to operate the controller 214 and othercircuitry and components of the ICM 108. For example, the powerdistribution circuitry 212 can rectify the AC signal or receive therectified AC signal from the front-end and communication circuitry 210,which in some instances is considered a direct current (DC) signal,therefore providing AC to DC conversion. In some embodiments, the powerdistribution circuitry 212 comprises the rectifier and/or a DC-to-DCconverter to generate one or more reference voltages (e.g., 5 V and/or3.3 V reference voltages, nominal). The power distribution circuitry canserve as a power distribution circuitry to the controller 214 and/orother components (e.g., analog circuits) within the ICM and/or on one ormore circuit boards within the ICM.

In some embodiments, the power control and switching circuitry 216 iscoupled with and controlled by the controller 214, while in otherembodiments, some or all of the power control and switching circuitry isincorporated into the controller. In operation, the power control andswitching circuitry 216 delivers the power to drive the current throughthe solenoid and controls the direction of the current flow through thesolenoid 310 as dictated by the controller. In some embodiments, thepower control and switching circuitry comprises a plunger activationcircuitry that directs a plunger drive signal into the solenoid, and insome embodiments, controls a direction of current through the solenoid.The plunger drive signal induces a magnetic field relative to thesolenoid to the plunger 312 to move relative to the solenoid causing theplunger to change positions between open and closed positions in openingand closing the valve. In some embodiments, the power control andswitching circuitry 216 comprises one or more switches or transistors(e.g., H-Bridge comprising four field effect transistors (FETs)) thatform an electrical path that is utilized to energize the ICM solenoidcircuitry 220 to control the current to flow in a “forward” direction orin a “reverse” direction through the solenoid 310. The ability to changethe direction of the current flow allows the ICM to retract or extendthe plunger 312 between the open and closed positions.

In some circumstances, it is desirable to confirm that a given ICM hasexecuted a turn on or turn off command. It can also be desirable to knowfor diagnostic purposes, what state a valve is currently in (open,closed, unknown, etc.) and/or a current position of a plunger 312relative to the valve. Accordingly, in some embodiments the ICM 108includes the PPDC 218 that is used to determine the location of theplunger. The PPDC 218 allows the controller 214 to determine and/orconfirm a location of the plunger 312 (e.g., open position, closedposition, and/or undetermined position), and thus, determine whether thevalve is in an open state, a closed state, another position and in someinstances an undetermined state. The controller 214 couples with thePPDC 218 to receive input from the PPDC identifying the position of theplunger 312 and/or providing information to the controller 214 to allowthe controller to determine the location of the plunger based at leastin part on the information provided.

In many implementations, the inductance of a solenoid varies based on aposition of the plunger relative to the solenoid. This variation ininductance can have an effect on the voltage across a solenoid and/or acurrent passing through the solenoid. In some embodiments, the PPDCapplies an input stimulus to the solenoid 310. The input stimulustypically does not cause the plunger to change positions or states, andin many embodiments does not cause the plunger to move from a currentposition. Further, in some embodiments, the input stimulus is applied toand/or injected into the solenoid at a time while a plunger drive signalis not being applied to the solenoid. The PPDC, in some embodiments,utilizes the input stimulus to estimate and/or determine a location ofthe plunger relative to the solenoid based, at least in part, from theresulting variations in inductance caused by the movement of the plungerrelative to the solenoid.

The solenoid circuitry 220 comprises the solenoid or bobbin (e.g.,including an inductor or coil) with which the plunger 312 is cooperated.The solenoid circuitry is electrically connected to power control andswitching circuitry 216 and the PPDC 218. As described above, the powercontrol and switching circuitry 216 controls the direction of currentthrough the solenoid 310, which induces a magnetic field that isconfigured to move the plunger between closed and open positions.

Some embodiments optionally further include the temperature sensorand/or sensing circuitry 224. In some alternative embodiments, one ormore temperature sensing circuitry 224 may be external to the ICM 108and communicate directly with the ICM, communicate with the centralcontroller 102 that provides temperature information to the ICM, orcommunicates with another device (e.g., another ICM) that forwards thetemperature information to one or more other ICMs or the centralcontroller. The temperature information allows the controller 214 and/orthe PPDC 218 to compensate for variations in measurements (e.g., voltageand/or current measurements) due to current temperature information. Forexample, the voltage and/or current through the solenoid 310 may varydepending on temperature. Accordingly, the controller 214 and/or thePPDC 218 can take into consideration these variations when determining arelative position of the plunger.

In some embodiments, the ICM 108 optionally further includes a power orvoltage boost circuitry or system 222. As described above with referenceto FIG. 1, multiple ICMs 108 are typically coupled at various locationsalong the length of the multi-wire path 106, with the multi-wire pathoften being hundreds to potentially tens of thousands of feet longallowing potentially hundreds to thousands of ICMs to be coupled along asingle multi-wire path. The ICMs typically derive operational power andpower to drive open and close the valve from the AC waveform receivedvia the multi-wire path 106. Because of the potential lengths of the oneor more multi-wire paths, the amplitude of the AC waveform is often lessas that ICMs are positioned further from the ICI 104 and/or other sourceof power received via the multi-wire path. Accordingly, the AC powersignal may provide insufficient power (e.g., insufficient voltage toopen and/or close the solenoid controlled valve) to one or more ICMspositioned away from the ICI and/or proximate an end of the multi-wirepath.

In some embodiments, the ICM can include the boost circuitry or system.In response to detecting that the voltage or power is insufficientand/or when it is detected that a level of the AC signal drops below athreshold, the boost circuitry 222 can be activated. The boost circuitrycomprises one or more energy storing devices to store energy that can beutilized when needed to, for example, at least boost the voltageretrieved from the multi-wire path 106 to effectively induce movement ofthe plunger 312 to open or close the valve even when the level of thesignal on the multi-wire path drops below a level that would otherwisebe insufficient to effectively move the plunger to a desired open orclosed position.

Some embodiments incorporate some or all of the circuitry onto one ormore circuit boards 314 incorporated into the ICM 108. Accordingly, theICM solenoid sub-assembly or circuitry 220 is configured to actuate andin some instances latch the physical position of the plunger when theplunger drive signal is applied to the solenoid (e.g., a defined amountof current is conducted through the solenoid). The plunger detection, insome embodiments, is configured such that it does not actuate or changethe physical position of the plunger.

FIG. 4 shows a simplified block diagram of exemplary circuitry or asystem comprising the PPDC 218, in accordance with some embodiments. Asdescribed above, the inductance of the solenoid typically varies basedon a location of the plunger relative to the solenoid, and the change ininductance can affect the voltage across the solenoid and/or the currentthrough the solenoid. Again, the solenoid 310 is configured to cooperatewith a plunger 312 and to receive a plunger drive signal from plungeractivation circuitry. The plunger drive signal induces a magnetic fieldrelative to the solenoid 310 that can cause the plunger 312 to changepositions between the open and closed positions. This change ofpositioning of the plunger causing an opening and closing of anirrigation valve 110 such that water is allowed to flow through aconduit 428 and through the valve when the plunger is in the openposition and water is prevented from passing the valve when the plungeris in the closed position. In some embodiments, the PPDC 218 comprisesan input stimulus source or circuitry 410, an input stimulusconditioning circuitry or system 412 that cooperates with the powercontrol and switching circuitry 216, and a sampling circuitry and/orcontrol circuitry 414. In some embodiments, the PPDC further includes orthe sampling circuitry 414 further includes an analog to digital (A/D)converter 416. Additionally, some embodiments optionally includefiltering and/or isolation circuitry 418, a gain stage circuitry orsystem 420, and/or other such circuitry.

The input stimulus source 410 injects the input stimulus into thesolenoid 310. As described above, in many embodiments the input stimuluswhen applied to the solenoid 310 is insufficient to cause the plunger312 to move from a current position. The input stimulus can be a signalthat establishes a voltage across the solenoid that can be sampled bythe sampling circuitry 414. For example, in some embodiments, the inputstimulus is a single 5 V pulse (e.g., square wave pulse) applied to thesolenoid. Again, the position of the plunger relative to the solenoidalters the inductance of the solenoid, and the voltage across thesolenoid typically changes because of the change in inductance resultingfrom the changing positions of the plunger. Through testing, voltagethresholds can be determined and/or defined that can be used insubsequent measurements of voltage to identify the relative plungerposition. Further, in some embodiments, the input stimulus source isimplemented through the controller 214. For example, the controller insome embodiments comprises a microcontroller that is configured togenerate the input stimulus and apply that to the PPDC. In otherembodiments, the input stimulus can be a train of pulses, a tone, a sinewave, a low-level step function, a spectrally rich signal with multiplefrequencies, or other such relevant inputs.

Some embodiments operate with pulse widths in the range of about 10 to500 microseconds (μs). Further, some embodiments operate with pulseamplitudes in the range of about 3 to 5 VDC. As described above andfurther below, some embodiments utilize multiple pulse input stimuli,for example, with pulse widths in the range of about 10 to 500 μs, withintervals in the order of microseconds to milliseconds (ms), and withpulse amplitudes in the range of about 3 to 5 VDC. Some embodimentsactivate an input stimulus a predefined delay after the plunger drivesignal is applied. The delay can be substantially any delay, such asfrom microseconds to minutes to hours, and typically the delay issufficiently long to allow the magnetic field, which was induced throughthe solenoid in response to the plunger drive signal to actuate theplunger, to collapse. It is noted that the execution of the plungerdrive signal or command is not necessary for initiating thedetermination of a location of the plunger, the execution of an inputstimulus or the application of the input stimulus. Further, the takingof one or more voltage measurements and/or current measurement aretypically delayed following the initiation of the input stimulus, whichcan range from microseconds to seconds or longer and may depend on theinput stimulus.

The PPDC 218, in some embodiments, includes the conditioning circuitry412 that cooperates with the solenoid 310 to condition the inputstimulus to provide a measurable parameter that is used in determiningthe location of the plunger. In some embodiments, the conditioningcircuitry 412 comprises a resistance-capacitance circuit (RC circuit)that in cooperation with the inductance of the solenoid 310 establishesan inductance, resistance and capacitance circuitry (LRC circuitry) orsystem 422. In other embodiments, a conditioning circuit may comprise aresistance to ground. Still other embodiments may utilize alternativeconditioning circuitry.

FIG. 5 depicts a representative simplified schematic diagram of LRCcircuitry 500, in accordance with some embodiments. The input stimulussource 410 applies the input stimulus (e.g., a relatively smallamplitude 5V DC pulse) to the LRC circuitry establishing a voltageacross the solenoid 310. In some embodiments, the resistance 512 is afix-value resistance provided by one or more resistors, and thecapacitance 510 is a fix-value capacitance provided by one or morecapacitors. The inductance of the solenoid 310 changes depending on theposition of the plunger, and accordingly, the position of the plungerrelative to the solenoid changes the voltage 514 across the solenoid.Therefore, when the input stimulus is applied to the LRC circuit, theLRC circuitry modulates the amplitude of the injected input stimulus asa function of the plunger position. In some embodiments, the LRCcircuitry 500 is a resonant circuit, but is not required to be aresonant circuit. The relative values of the resistance, capacitance andinductance will dictate whether or not the circuit is resonant. FIG. 5shows the LRC circuitry 500 as a series coupled LRC circuitry. Otherembodiments, however, utilize parallel coupled LRC circuitry.

Referring back to FIG. 4, some embodiments include the A/D converter 416that converts the analog voltage across the solenoid into digitalrepresentations of the voltage. In some embodiments, the A/D converteris implemented in the controller 214 (e.g., as part of a microcontroller(MCU)), while in other embodiments, the A/D converter is external to thecontroller. The sampling circuitry 414 couples with the A/D converter totake one or more measurements of the voltage that correspond to thevoltage across the solenoid.

The sampling circuitry or the controller 214 utilizes the one or morevoltage measurements to determine a position of the plunger relative tosolenoid. In some embodiments, the controller 214 has one or morevoltage thresholds corresponding to expected voltages across thesolenoid when the plunger is in the closed position, and/or the openposition. Other thresholds may also be defined, such as corresponding toone or more other plunger positions, when the plunger is removed fromthe solenoid, and other such thresholds. Accordingly, the controller 214can evaluate the one or more voltage measurements relative to the one ormore voltage thresholds and based on the resulting relationship(s)between the measured voltage(s) and the threshold(s) determine whetherthe plunger is in a closed position, an open position or other position.Some embodiments are configured to determine a relative quality of openor closed state. For example, in some implementations, the controllerdetermines a proportional location of the plunger relative to one of theopen and closed positions and a range of motion of the plunger. Otherembodiments identify a plunger location based on the plunger detected asbeing within a zone or range of positions of a plurality of zones orranges distributed along the path of motion of the plunger.

The PPDC 218 can also include, in some embodiments, the gain stage 420that is cooperated with the terminal of the solenoid 310. Typically, thegain stage is positioned between the solenoid and the A/D converterand/or sampling circuitry. In some implementations, the gain stageincludes one or more amplifiers and/or amplifying circuitry. The gainstage is configured to amplify or increase the amplitude-modulated pulseresulting from the LRC circuitry 422 in response to the input stimulus.An amplified, amplitude-modulated pulse is produced or otherwisegenerated corresponding to voltage across the solenoid. Theamplification allows for the utilization of a greater or full dynamicrange of the A/D converter 416, the sampling circuitry and thecontroller. The increased range allows the A/C converter to utilize anincreased resolution and in some embodiments approach its entireresolution (e.g., 12-bits of resolution), which can result in increasedaccuracy of the voltage measurements obtained by the sampling circuitry414. In some embodiments, the sampling circuitry in measuring the one ormore voltage measurements is configured to measure the one or morevoltage measurements of the amplified, amplitude-modulated pulsecorresponding to the voltage across the solenoid with a resultingincreased dynamic range of the sampling circuitry allowing theutilization of a greater number of bits to digitally represent thesampled signal than available without the gain stage.

Some embodiments further include filtering and/or isolation circuitry418. In some implementations, a filtering circuitry helps to shape theinput stimulus (e.g., a pulse, a series of pulses, a sine wave, etc.)and/or to limit the frequency content of the input stimulus. Someembodiments include isolation circuitry that provides isolation of theinput stimulus source 410 (e.g., a pulse waveform source) from the LRCcircuitry 422. Similarly, in some implementation the gain stage 420provides isolation of the A/D converter 416 and/or the control and/orsampling circuitry 414 from the LRC circuitry. Some embodiments include,as at least part of the isolation circuitry 418, a buffer, a unity-gainamplifier follower and/or other such isolation devices or circuitry.

FIG. 6 shows a simplified flow diagram of an exemplary process 610 ofdetermining a location of a plunger 312 that opens and closes a valverelative to a solenoid 310, in accordance with some embodiments. In step612, an input stimulus is applied to the solenoid. In some embodiments,the controller generates the input stimulus and/or activates a separateinput stimulus generator or source so that the input stimulus is appliedto the solenoid 310, which in some embodiments includes applying theinput stimulus through the PPDC 218 and/or the conditioning circuitry412. As described above, in many embodiments, the input stimulus is ofan insufficient level to cause the plunger to change positions orstates.

In step 614, one or more voltage measurements are taken and/or sampledacross the solenoid in response to the input stimulus being applied tothe input stimulus conditioning circuit and the solenoid. Again, thepositioning of the plunger affects the inductance of the solenoid, andaccordingly the voltage of the one or more voltage measurements inresponse to the input stimulus applied to the solenoid are dependentupon the state and/or position of the plunger relative to the solenoid.Further, in some embodiments, some or all of the voltage measurementsare taken at least a predefined period of time following the applicationof the input stimulus to the solenoid. For example, in someimplementations, the one or more voltage measurements are taking within1-4 seconds following the input stimulus being applied to the solenoid.Furthermore, the input stimulus is typically applied to the solenoid ata time while the plunger drive signal is not being applied to thesolenoid.

In step 616, the one or more voltage measurements are evaluated. In manyembodiments, the evaluation includes evaluating the one or more voltagemeasurements relative to one or more thresholds. In step 618, it isdetermined whether the plunger is in one of the open position and theclosed position based on the evaluation of the one or more voltagemeasurements. Some embodiments are additionally configured to determinethe plunger is positioned between the open and closed positions, ordetermine that the plunger is removed from the solenoid based on theevaluation of the one or more voltage measurements. In someimplementations a position of the plunger is determined as a result of arelationship between the one or more voltage measurements and one ormore thresholds. For example, in some embodiments, the one or morevoltage measurements or some combination of two or more voltagemeasurements are compared to a threshold, and when determined thethreshold is exceeded the plunger is considered to be in a closedposition and when not exceeded the plunger is considered to be in anopen positioned. Similarly, in some embodiments the one or more voltagemeasurements are evaluated relative to a closed voltage threshold, whichcorresponds to a voltage that is approximately equal to (or within arange of) a voltage level that is expected when the plunger is in theclosed position, in determining whether the one or more voltagemeasurements are within a range of the closed voltage threshold.Additionally or alternatively, in some embodiments, the one or morevoltage measurements are evaluated relative to an open voltagethreshold, which corresponds to a voltage that is approximately equal to(or within a range of) a voltage level that is expected when the plungeris in the open position, to determine whether the one or more voltagemeasurements are within a range of the voltage threshold correspondingto the open position.

In some embodiments, the location of the plunger can be determined as anundetermined or unknown position. For example, when the one or morevoltage measurements are not within a predefined range of the closevoltage threshold and not within a predefined range of the open voltagethreshold, the controller can determine that that plunger is in anundetermined position, and instead between the open and closedpositions. Other embodiments, however, may utilize additionalthresholds, tables, ranges and/or other parameters to evaluate the oneor more voltage measurements to more accurately determine a location ofthe plunger, including when the plunger is not at one of the open orclosed positions.

In some implementations, the PPDC and/or controller are configured todetermine a proportional location of the plunger relative to one of theopen and closed positions and a range of motion of the plunger. Forexample, some embodiments determine of a level or quality of how opendefined by an estimated proportional position of the plunger relative toa range of motion of the plunger and a fully open position at a firstlimit of the range of motion of the plunger, or a level or quality ofhow closed defined by an estimated proportional position of the plungerrelative to the range of motion of the plunger and a fully closedposition at a second limit of the range of motion (e.g., a percentage ordistance relationship, such as 80% closed, 60% open, etc.). Accordingly,some embodiments are configured to determine that the plunger is locatedat an alternate position that is between the open position and theclosed position. Still further, some embodiments are configured toidentify that the plunger is within a first range of a plurality rangesof positions spaced along a range of motion of the plunger. Theprecision in identifying the location of the plunger is dependent on thesize of the plurality of ranges. In some instances where the ranges maybe substantially the same across the range of motion, while in otherinstances the plurality of ranges may vary over the range of motion ofthe plunger.

Additionally, some embodiments are configured to determine whether theplunger is removed from cooperation with the solenoid. The one or morevoltage measurements can be evaluated relative to an additionalthreshold corresponding to a voltage expected across the solenoid whenthe plunger has been removed. In other instances, the controller candetermine the plunger is removed based on the relationship of the one ormore voltage measurements relative to one or both of the open voltagethreshold and the closed voltage threshold (e.g., the voltage across thesolenoid is greater than the closed voltage threshold by more than apredefined margin or range). In some embodiments, the controller 214 isconfigured to communicate the determined plunger position back to theICI 104 and/or central controller 102, allowing the central controllerto make adjustments to irrigation scheduling, provide notifications(e.g., signal an error), and/or take other action.

FIG. 7 illustrates a simplified block diagram of an exemplary circuitryor system comprising the PPDC 218 in accordance with some embodiments.The PPDC 218 receives the input stimulus from and/or comprises an inputstimulus source 410. For example, the controller 214 and/or amicrocontroller can generate the input stimulus and/or activate aseparate stimulus source. Some embodiments include an input stimulusconditioning circuitry or system 412 that cooperates with the powercontrol and switching circuitry. The switching circuitry dictates thedirection of current through the solenoid 310, and thus, the directionof movement of the plunger 312 to the open position or the closedposition.

In some embodiments, the switching circuitry comprises, for example, anH-bridge switching circuitry with a first half of an H-bridge switchingcircuitry 712 cooperated with a first terminal of the solenoid 310 and asecond half of the H-bridge circuitry 714 cooperated with a secondterminal of the solenoid. The H-bridge is controlled by the controller214 to dictate a direction of the current flow through the solenoid 310to control the extension and retraction of the plunger 312 between theopen and closed positions. Similar to the embodiment depicted in FIG. 4,the embodiment illustrated in FIG. 7 may also include, in someembodiments, the A/D converter 416. Further, some embodiments mayoptionally include the filtering and/or isolation circuitry 418, thegain stage 420 and/or other relevant circuitry and/or systems.

FIG. 8A shows a circuit diagram of exemplary circuitry or a systemcomprising a PPDC 218, in accordance with some embodiments. The inputstimulus source 410 couples with a filtering and isolation circuitry 418that passes the input stimulus to the conditioning circuitry 412, whichcomprises RC circuitry. A first terminal of the solenoid 310 coupleswith the RC circuitry to receive the input stimulus. A gain stage 420 isalso coupled with the first terminal of the solenoid 310, and amplifiesthe voltage across the solenoid. The amplified voltage is received atthe sampling circuitry 414, which in some embodiments includes an A/Dconverter, to take one or more voltage measurements of the voltagecorresponding to the voltage across the solenoid. The gain stage in partallows for the use of an increased dynamic range of the samplingcircuitry and/or the utilization of a greater number of bits todigitally represent the sampled signal than available without the gainstage.

A first half of an H-bridge switching circuitry 712 also couples withthe first terminal of the solenoid, while a second half of the H-bridgecircuitry 714 couples with a second terminal of the solenoid. TheH-bridge switching circuitry is controlled by the controller 214. Again,in operation, the H-bridge circuitry switches the plunger drive signal(e.g., current pulse) to open or close the corresponding irrigationvalve 110. For example, the controller 214 can be configured to generateswitching control signals 810-813 that are applied to the first andsecond halves of the H-bridge switching circuitry (e.g., one or more of:an off-high signal 810 applied to a gate of a first transistor 816 ofthe first half of the H-bridge circuitry 712 that in turn controls avoltage at a gate of a first switch of a first two-switch switchingcircuitry, device or system 820 (e.g., MOSFET switching circuitry); anon-low signal 811 applied to a gate of a second switch of the firsttwo-switch switching circuitry 820; an on-high signal 812 applied to agate of a second transistor 818 of the second half of the H-bridgecircuitry 714 that in turn controls a voltage at a gate of a firstswitch of a second two-switch switching circuitry, device or system 822;an off-low signal 813 applied to a gate of a second switch of the secondtwo-switch switching circuitry 822). The switching controls signals810-813 can control whether the plunger is driven to the open or closedposition, which in turn opens or closes the valve. For example, in someimplementations when implementing a valve on plunger drive signal (i.e.valve is open) the on-low signal 811 can be applied as a logical lowsignal while the on-high signal 812 can be applied as a logical highsignal. Similarly, in some implementations, when applying a valve offplunger drive signal (i.e., valve is closed) the off-high signal 810 canbe applied as a logical high signal, and the off-high signal 810 can beapplied as a logical high signal.

The filtering and isolation circuitry 418 of FIG. 8A includes afiltering circuitry comprising RC filter circuitry with a filterresistance 830 and filter capacitance 832. The values of the filterresistance and filter capacitance provide at least some control over ashape of the input stimulus and/or to limit the frequency content of theinput stimulus (e.g., filtering edges on a square pulse). Someembodiments include an amplifier circuitry 834 (e.g., operationalamplifier, transistor(s), etc.) that operates as a follower with aunitary gain, which in some instances can further provide some isolationof the input stimulus source 410 from the LRC circuitry. Accordingly,the input stimulus source (e.g., a microcontroller) is isolated from andeffectively cannot see (or is not affected by) the impedance of thesolenoid of by LRC circuit. In some embodiments, the filtering and/orisolation circuitry includes a limiting resistance 836 that can beconfigured to limit an amplitude of the input stimulus to a desiredlevel, such as a predefined threshold. In some embodiments the limitingresistance maintains a maximum output of the amplifier (e.g., to avoltage of about 1.6 V, in some implementations).

Some embodiments may include one or more additional protectioncircuitry. For example, some embodiments may include a diode 838 coupledrelative to the conditioning circuitry 412 and/or the amplifiercircuitry 834. The diodes can provide protection for the isolationcircuitry 418 from higher voltages that may appear at a circuit node ofthe isolation circuitry when the switching circuit is executing theactuation of the plunger.

In some embodiments, the conditioning circuitry 412 includes one or moreresistors providing a conditioning resistance 840 and one or morecapacitors providing the conditioning capacitance 842 such that theconditioning circuit comprises an RC circuitry. The RC circuitry isshown coupled in series with the solenoid 310. In other embodiments,however, the RC circuitry may be coupled in parallel with the solenoid.The value of the conditioning resistance 840 and conditioningcapacitance 842 can be selected to provide for a resonant circuit, witha value of inductance of the solenoid 310 when the plunger is in a knownposition (e.g., closed position), the resistance of the conditioningresistance 840 and the capacitance of the conditioning capacitance 842dictating whether or not the circuit is resonant. As described above, insome implementations the resistance 840 is a fix value resistor and thecapacitance 842 is a fixed value capacitor.

Again, some embodiments optionally include the gain stage circuitry orsystem 420. In some implementations, the gain stage comprises amplifiercircuitry 850 (e.g., an operational amplifier, transistor(s), etc.) thatamplifies the voltage for sampling by the sampling circuitry 414. Thegain of the amplifier 850 is controlled by the gain resistors 852 and854. The gain stage increases the signal for sampling, and in someinstances increases the signal to near full scale to increase and insome instances maximize resolution and/or allowing higher precision inthe voltage measurements. Further, in some embodiments, the gain stageprovides a low impedance source to drive the sampling circuitry (e.g., asample and hold internal to the controller), which can help in reducingand/or eliminating sampling errors. Some embodiments may further includeone or more additional protection circuitry. For example, someembodiments may include a diode 858 coupled relative to the conditioningcircuitry 412 and/or the gain stage circuitry 420. Similar to the diode838, the diodes 858 can provide protection for the gain stage circuitryfrom higher voltages that may appear at a circuit node of the gain stagecircuitry when the switching circuit is executing the actuation of theplunger. Although FIG. 8A shows the diodes 838, 858 as part of theisolation circuitry 418 and gain stage circuitry 420, respectively, insome embodiments, the diodes may be stand-alone components, may be partof the conditioning circuitry 412, or may be part of other circuitry.

In operation, current is applied to the PPDC through the input stimulussource 410 passing through the filtering and/or isolation circuitry,which again can shape the input stimulus and/or isolate the inputstimulus source. Following the isolation and/or filtering, whenincluded, the current enters the conditioning circuitry 412 (e.g., RCcircuitry comprising resistance 840 and capacitance 842). Typically, thecurrent passes through the first half of the H-bridge circuitry 712 tobe applied to the solenoid 310. In some embodiments, the current thencontinues to ground through the second half of the H-bridge circuitry714 (e.g., the second two switch switching circuitry 822 can beconfigured and/or programmed such that the current flows from a drain toa source of a MOSFET and to ground). Again, the input stimulus issufficiently low that it does not cause the plunger to move.

In some embodiments, the sampling circuitry 414 takes one or morevoltage measurements through a stimulus response curve. FIG. 9 shows agraphical representation 910 of the resulting voltage over time as seenacross the solenoid in response to a square pulse input stimulus (e.g.,5 V, 10 μs pulse width) in accordance with some implementations when theplunger is in the open position (e.g., with at least a majority of theplunger generally within of the solenoid), and a graphicalrepresentation 912 of the resulting voltage over time as seen across thesolenoid in response to a square pulse input stimulus (e.g., 5 VDC, 10μs pulse width) in accordance with some implementations when the plungeris in the closed position (e.g., with at least a majority the plungerpositioned substantially out of the solenoid). Further, the graphicalrepresentations 910 and 912 are based on measurements taken by throughan A/D converter (e.g., within the controller 214) following a gainstage circuitry (e.g., gain stage 420). Multiple measurements 914 orsamples are taken over time of the voltage across the solenoid inresponse to the application of the input stimulus to the solenoid (e.g.,injection into the LRC circuit). In some embodiments, the multiplevoltage measurements made through the stimulus response curve help withnoise immunity and increase the absolute magnitude difference betweenthe two plunger positions or states. Further, in some embodiments, twoor more of the multiple measurements can be combined and the combinedvalue can be compared to the one or more thresholds in determiningwhether the plunger is in the open position, closed position or otherposition. For example, the multiple voltage measurements taken over theresponse curve and/or time can be summed. In other embodiments, two ormore voltage measurements are averaged. Again, the combined value can becompared to one or more thresholds and/or ranges in determining alocation of the plunger. Other such combining and/or other mathematicalequations can be applied to combine the one or more voltage measurementsthat can be evaluated to determine a location of the plunger (e.g.,based on a comparison to one or more thresholds, a mapping betweencombined measurements and corresponding position information, one ormore tables associating cooperated measurements with plunger locations,a relationship between a range of combined measurements and a range oflocations, etc.).

The distance between the resulting voltage measurements when the plungeris in the different positions allows the controller to evaluate thevoltage measurements relative to one or more thresholds in determining aposition of the plunger. For example, a first threshold can correspondto an approximate voltage across the solenoid when the plunger is in theclosed position (e.g., measured voltage is greater than a firstthreshold), and a second threshold can correspond to an approximatevoltage expected across the solenoid when the plunger in the openposition (e.g., measured voltage is less than a second threshold).Similarly, the one or more thresholds may include or correspond to oneor more threshold curves or graphs 918, 920 that correspond to theexpected stimulus response voltage curve measured across the solenoid(e.g., an open threshold curve 918, and a closed threshold curve 920).Again, some embodiments evaluation one or more measurements and/orcooperated measurements relative to one or more thresholds. Additionallyor alternatively, in some embodiments, the controller 214 is configuredto evaluate measurements relative to ranges, and to identify the plungeras being at a location when the plunger is determined to be within a onerange of a plurality ranges of positions distributed along and within arange of motion of the plunger.

FIG. 10 shows a graphical representation of a corresponding voltage overtime 1010 across the solenoid and prior to a gain stage in response tothe input stimulus when the plunger is in the closed position (out ofthe solenoid), and a graphical representation of a corresponding voltageover time 1012 across the solenoid in response to the input stimuluswhen the plunger is in the open position (in the solenoid).

FIG. 8B shows a circuit schematic of exemplary circuitry or a systemcomprising a PPDC 218, in accordance with some embodiments. Filteringand/or isolation circuitry 418 receives the input stimulus from an inputstimulus source 410, and couples with conditioning circuitry 412. Afirst terminal of the solenoid 310 couples with the conditioningcircuitry through switching circuitry 712, 714. A gain stage 420 is alsocoupled with the first terminal of the solenoid 310, and amplifies thevoltage across the solenoid. The amplified voltage is received atsampling circuitry 414, which in some embodiments includes an A/Dconverter, to take one or more voltage measurements of the voltagecorresponding to the voltage across the solenoid.

The filtering and/or isolation circuitry 418, in some embodiments,includes a filtering circuitry comprising RC filter circuitry with afilter resistance 830 and filter capacitance 832. As described above,the values of the filter resistance and filter capacitance provide atleast some control over a shape of the input stimulus and/or to limitthe frequency content of the input stimulus (e.g., filtering edges on asquare pulse). Further, some embodiments include isolation circuitry870. For example, some implementations include one or more transistors(e.g., bipolar junction transistor(s) (BJT), or other such transistor ortransistors) that provide some isolation of the input stimulus source410 from the LRC circuitry. Accordingly, in some implementations, theinput stimulus source (e.g., a microcontroller) is isolated from andeffectively cannot see (or is not affected by) the impedance of thesolenoid of by LRC circuit. A voltage, Vcap, is connected to one or moreenergy storage devices (e.g., capacitors, batteries, rechargeablebatteries, etc.) or other voltage source. The application of the inputstimulus activates the transistor to switch on and modulates the voltagefrom the application of the energy storage devices or other sourcevoltage to the conditioning circuitry 412, first half of the H-bridgeswitching circuitry 712, solenoid 310 and second half of the H-bridgeswitching circuitry 714 in determining a location of the plunger.

In some embodiments, the switching circuitry is similar to the switchingcircuitry of FIG. 8A, and includes a first half of an H-bridge switchingcircuitry 712 that couples with the first terminal of the solenoid,while a second half of the H-bridge circuitry 714 couples with a secondterminal of the solenoid. The H-bridge switching circuitry can becontrolled by the controller 214 or other relevant switch controller.

Again, some embodiments optionally include the gain stage circuitry orsystem 420. In some implementations, the gain stage comprises amplifiercircuitry 850 (e.g., an operational amplifier, transistor(s), etc.),where a gain of the amplifier 850 is controlled by the gain resistors852 and 854. In operation, current is applied to the PPDC through theinput stimulus source 410 passing through the filtering and/or isolationcircuitry 418, which again can at least help in shaping the inputstimulus and/or isolate the input stimulus source. Following theisolation and/or filtering, when included, the current enters theconditioning circuitry 412 (e.g., RC circuitry comprising resistance 840and capacitance 842). Typically, the current passes through the firsthalf of the H-bridge circuitry 712 to be applied to the solenoid 310. Insome embodiments, the current then continues to ground through thesecond half of the H-bridge circuitry 714. In some embodiments, thesampling circuitry 414 takes one or more voltage measurements through astimulus response curve.

Further, the timing of when the one or more voltage measurements aretaken is typically controlled by the controller 214, and is typicallydependent on the expected range of inductance of the solenoid, and canalso be dependent upon the conditioning circuitry 412 and/or the inputstimulus. In some embodiments, one or more measurements may be takensimultaneously as the input stimulus is applied, in some instances oneor more voltage measurements are taken at a termination of an inputstimulus (e.g., at a falling edge of a plus), one or more voltagemeasurements may additionally or alternatively be taken some delayedtime period following the application of the input stimulus. The delaybetween the application and/or termination of the input stimulus and thetiming of the one more measurements can be a few microseconds or more.For example, in many instances, the input stimulus applied is a singlepulse having a fixed duration (e.g., 50 μs). As such, the controllerhaving knowledge of the input stimulus can delay the one or moremeasurements to approximately a conclusion of the pulse, sometime duringthe pulse, a time just following the pulse (e.g., starting at about52-56 μs), or other such delays. The timing can take into considerationreactance of circuit components (e.g., the inductance of the solenoid).

In some embodiments, the basic measurement circuitry used to detect theplunger is relatively simple, based on expected inductance valuedifferences corresponding to different plunger positions. Thisinductance difference is caused by the different plunger positionsrelative to the coil. Observations from tested, manufactured coils showa “plunger in” inductance value to be approximately 18.5 mH and the“plunger out” to be approximately 26 mH. The inductance values aremeasured by a small stimulus, too small to provide motive force on theplunger, and in some embodiments routed through an LRC circuit. Testingcan be performed to identify one or more thresholds that cansubsequently be utilized in determining thresholds (e.g., a closedvoltage threshold and/or an open voltage threshold).

One or more measurements can be made through the stimulus response curveto help with noise immunity and to increase the absolute magnitudedifference between the two states as illustrated in FIG. 9. A gain stagecan, in some embodiments, be configured to provide a low impedancesource to drive the internal sample and hold, which can reduce oreliminate sampling errors. Further, the gain stage can increase thesignal to near full scale to maximize resolution.

Referring back to FIGS. 7 and 8, and as described above, in someembodiments the RC circuitry and the solenoid 310 establish the LRCcircuitry. The value of the conditioning resistance 840 and conditioningcapacitance 842 can be selected to provide a resonant circuit when theplunger is in a predefined position such that the inductance of thesolenoid in relation to the selected resistance and capacitance dictatesthat the LRC circuitry is a resonant circuit. As the inductance of thesolenoid changes, however, due to a change in position of the plungerthe LRC circuitry no longer acts as a resonant circuit. As such, someembodiments utilize the resonant aspect of the established LRC circuitryin determining a location of the plunger relative to the solenoid.

In some embodiments, the response to an input stimulus can be measuredto determine whether a resonant response is detected. For example, insome implementations, an amplitude of the response from the LRCcircuitry is tracked or otherwise sampled to determine whether theamplitude has a predefined relationship with one or more amplitudethresholds. When the resonant circuit is established the LRC circuitryresponse typically results in a peak amplitude. As such, based onmeasured LRC circuitry response, the controller can determine whetherthe plunger is in the predefined position.

Further, some embodiments are configured to determine different plungerpositions relative to the solenoid by configuring the system to utilizea range of frequencies that can be tracked as different resonantfrequencies each typically correspond to a different inductance of thesolenoid and thus different plunger positions. As is understood in theart, a resonant frequency (ω_(o)) equals 1 over root squared ofinductance times capacitance (i.e., ω_(o)=1/√LC), where the resonantfrequency is in radians per second. So when a resonance condition occursthe measured voltage (e.g., at the A/D converter 416) peaks versus whenresonance does not occurs (i.e. when it does not occurs at ω_(o)), wherethe resonant frequency typically is depended on the inductance (L value)of the solenoid 310. In some embodiments, the input stimulus is a sinewave signal, a periodic square wave signal or other such relevant signalthat is set at the resonant frequency, or at one of potentially severaldifferent frequencies that each correspond to a different plungerposition. The controller 414, in some embodiments, is configured todetect the resonance peak at the resonant frequency or the absence ofthe resonant response indicating the plunger is a predefined position(e.g., an open position when the resonant response is detected and aclosed position when the resonant response is not detected, or at someposition between open and closed as a function of the response relativeto the resonant response).

In some embodiments, the controller is further configured to detect overa range of frequencies to allow the plunger position to be moreprecisely tracked. In such configurations, the resonant frequency of theinput stimulus can be varied, where different resonant frequenciescorrespond to different plunger locations (i.e., correspond to thedifferent inductances of the solenoid based on the position of theplunger relative to the solenoid). As such, the controller can estimatea plunger location from a fully closed position, to a fully openposition, one or more positions between fully open and fully closed, andin some instances when the plunger is removed, based on applyingdifferent resonant frequency input stimulus signals and the detection ofa resulting resonant response (e.g., tracking voltage peaks whichcorrespond to a given resonant frequency, ω_(o)).

FIG. 11 shows a simplified flow diagram of an exemplary process 1110 toidentify a location of the plunger based on a resonant response to theinput stimulus, in accordance with some embodiments. In step 1112, aninput stimulus is injected or applied to the solenoid. The inputstimulus can be a pulse, a train of pulses, a tone, or other suchrelevant inputs that can induce a resonant response from the LRC circuitwhen the plunger is in a position to establish an inductance that allowsthe LRC circuit to generate the resonant response. In some embodiments,the application of the input stimulus can include applying an inputstimulus signal that changes its resonant frequency over time, ormultiple input stimulus signals having different resonant frequenciesmay sequentially be applied. In step 1114, it is determined whether aresonant response is detected in response to the input stimulus. In someembodiment, one or more voltage measurements relative to the solenoidand/or across the solenoid are taken. The controller 214 can beconfigured to evaluate the one or more voltage measurements to determinewhether a resonant response is detected. For example, the controller cancompare the one or more voltage measurements, voltage amplitude and/orpeak measurements to one or more predefined amplitude thresholds thatcorrespond to predicted amplitude when the plunger is in the predefinedposition and the resonant response is generated in response to the inputstimulus. As described above, some embodiments apply different inputstimulus signals having different resonant frequencies. Accordingly,some embodiments may repeat steps 1112 and 1114 any number of times withdifferent resonant frequencies to identify when a resonant response isdetected.

In step 1116, a position of the plunger is estimated. In some instances,this includes determining whether the plunger is in the open or closedposition based on a determined relationship between the peak voltage andone or more voltage threshold. Some embodiments are configured todetermine whether the resonant response is detected, and/or a degree ofthe resonant response detected that corresponds to partially openpositions. In some embodiments, the resistance and capacitance of theresonant circuitry are selected to correspond with the inductance of thesolenoid when the plunger is in a predefined position, such as in theclosed position, when the input stimulus is applied with the relevantresonant frequency. When the resonant response is detected the plungeris determined to be in the predefined position corresponding to theresonant frequency of the input stimulus and the inductance of thesolenoid (e.g., the closed position), and when the resonant response isnot detected the plunger is not in the predefined position (e.g., theopen position or in another position). As described above, someembodiments may vary the resonant frequency of the input stimulus toprovide a more precise identification of the position of the plunger.

Further, in some embodiments, the control circuitry or controller isconfigured to determine a voltage amplitude of a response generated bythe resonant circuit in response to the input stimulus and determinewhether the resonant response is generated by, at least in part,comparing a peak voltage to a voltage threshold, and determining whetherthe resonant response is generated based on a determined relationshipbetween the peak voltage and the voltage threshold. Similarly, someembodiments measure one or more voltage measurements corresponding toone or more voltages across the solenoid, e.g., through samplingcircuitry, and the control circuitry is further configured to evaluatethe one or more voltage measurements relative to a second threshold, anddetermine the location of the plunger as a function of a relationshipbetween the one or more voltage measurements and the second threshold.The identification of a location, in some instances includes identifyingthe plunger is in an unknown position (e.g., not in the open positionand not in the closed position) as the result of a determinedrelationship between the peak voltage and its relationship with one ormore thresholds. Some embodiments apply an alternate input stimulus intothe solenoid, determine whether the resonant response is generated inresponse to the alternate input stimulus, and determine that the plungeris removed from a position cooperated with the solenoid in response towhether the resonant response is generated based on the alternate inputstimulus.

Some embodiments inject an input stimulus that is in the frequencydomain. For example, some embodiments employ a tone signal, sine wave(e.g., through a digital to analog converter), periodic square signal,or the like as the input stimulus. In some implementations, a tonesignal is configured as a signal that oscillates at a fixed frequency(e.g., a sine wave), having a spike or tone at a given frequency whenconsidered and/or evaluated in the frequency domain. Other embodimentsapply an input stimulus comprising multiple tones and/or spanning afrequency spectrum. Further, the sampling circuitry and/or circuitrytaking the one or more voltage measurements may be configured to takethe one or more voltage measurements as they vary with frequency.

Depending on the position of the plunger relative to the solenoid, theamplitude of the tone is amplitude modulated (i.e. attenuated). Inresponse to the application of the tone input stimulus, one or morevoltages can be measured, and typically multiple voltage measurementscorresponding to the voltage across the solenoid are taken over time inresponse to the tone input stimulus being applied to the solenoid. Thevoltage measurements can be taken similar to those described above. Theone or more voltage measurements are then evaluated to determine thelocation of the plunger. For example, in some implementations, theamplitude of the modulated tone is determined and/or an amount ofattenuation can be detected. Based on the determined amplitude and/orattenuation, and the frequency of the input stimulus, a location of theplunger can be determined, e.g., through a relationship with one or morethresholds, a mapping of attenuation to plunger position, a mapping ofamplitude to plunger position, or other such evaluations and/orcombinations thereof. Again, some embodiments identify whether theplunger is in one of the open or closed position, whether the plunger isin an undetermined position, and/or whether the plunger is removed fromthe solenoid. Further, some embodiments may provide more precision toidentify a location of the solenoid within a given range, identify arelative location of the plunger (e.g., 80% open, 35% closed, etc.) orother such more precise location identification.

FIG. 12 depicts a simplified block diagram representation of exemplarycircuitry forming at least part of the PPDC 218, in accordance with someembodiments. The circuitry utilizes a determined inductances inidentifying a position of a plunger 312 relative to the solenoid 310.The circuitry includes an input stimulus source 410, switching circuitrysuch as first and second half H-bridge switching circuitry 712 and 714,resistance circuitry 1212 or other such relevant conditioning circuit,and sampling and/or control circuitry 414. Some embodiments optionallyinclude filtering and/or isolation circuitry 418, a gain stage oramplifying circuitry 420, an A/D converter 416 and/or other suchcircuitry.

The solenoid 310 is configured to cooperate with a plunger 312 (notshown in FIG. 12). Further, the solenoid is configured to receive theplunger drive signal from a plunger activation circuitry (not shown).The plunger drive signal induces a magnetic field generated relative tothe solenoid that in turn can cause the plunger to change positionsbetween open and closed positions. Again, the transition of the plungercorresponds to an opening and closing of the irrigation valve coupledwith the plunger. The H-bridge circuitry 712, 714 couples with thesolenoid, and depending on switch orientation as activated andcontrolled by the controller 214, dictates the direction of current flowthrough the solenoid. The direction of current of the plunger drivesignal applied by the plunger activation circuitry controls thedirection of movement of the plunger between the open and closedposition and whether the plunger is in the open or closed position.

The input stimulus source 410 generates and/or directs an input stimulusto be applied to a first terminal of the solenoid. In some embodiments,the input stimulus source is implemented on the controller 214 (e.g., amicrocontroller). Typically, the input stimulus is applied to thesolenoid at a time when the plunger drive signal is not being applied tothe solenoid. Further, the input stimulus typically does not cause theplunger to change from a current position. In some implementations, theinput stimulus is a pulse, such a single square pulse with a fixedduration. Other embodiments may apply a train of pluses, while yet otherembodiments may utilize a sine wave oscillator and apply a sine wave orother such waveforms.

The resistance circuitry 1212 cooperates with the solenoid 310. In someembodiments, the resistive circuitry is coupled with a second terminalof the solenoid, such as through one or more switching circuitry thatcouple and decouple the resistance circuitry 1212 with the solenoid orotherwise provide a lower resistance path. Further, in some embodiments,the resistance circuitry 1212 comprises a precision, low tolerance,fix-value resistor or other relevant circuitry. The known resistances ofthe resistance circuitry can be utilized to indirectly calculate theelectrical current flowing through the inductor.

In some embodiments, the solenoid 310 is selectively coupled in serieswith the resistance circuitry 1212 providing a resistive load. Thesampling circuitry 414 is coupled with the second terminal of thesolenoid and/or the resistance circuitry, and is configured to take oneor more voltage measurements across the resistive load, at least inresponse to the input stimulus being applied to the solenoid. In someimplementation, the one or more voltage measurements of the voltageacross the resistance circuitry 1212 are taken while the input stimulusis being applied to the solenoid, at about the termination of the inputstimulus (e.g., approximately at a falling edge of a pulse inputstimulus) while current is passing through the solenoid in response tothe input stimulus, after a predefined delay after applying the inputstimulus or other such timing. The control circuitry 214 couples withthe sampling circuitry to receive the one or more voltage measurementsand determines a current passing through the resistive load as afunction of the one or more voltage measurements and the resistance ofthe resistance circuitry.

The controller 214, in some embodiments, is configured to determine aninductance of the solenoid as a function of the determined current and atiming of the input stimulus. In some implementations, the controllerexploits the equation V=di/dt*L. Utilizing the measured one or morevoltage measurements measured across the resistance circuitry 1212, thevoltage is known, and the inductance becomes proportional to a change incurrent over time (e.g., L=V/di/dt). The duration, duty cycle and/orfrequency of the input stimulus is known and can be used to determineand/or estimate the change in current (di/dt). For example, a pulseinput stimulus having a duration of 10 μs can be applied to a solenoidhaving an unknown inductance value based on an unknown position of theplunger relative to the solenoid. The one or more voltage measurementsare made across the current sense resistance circuitry 1212, typicallyat time proximate an end of the pulse. With the known resistance and themeasured voltage, the current is calculated. Knowing the time that thevoltage was applied and/or the pulse duration, the change in current canbe estimated, for example as a function of the measured voltage, theresistance and the duration of the pulse (e.g.,di/dt≈(V_(measured)/R)/10 μs).

Based on the determined change in current over time and the voltage ofthe input stimulus (V_(stimulus)), the controller can calculate anestimated inductance (L) of the solenoid at the time the input stimuluswas applied to the solenoid (e.g., L=(V_(stimulus))/(di/dt)). Thecontroller can then evaluate the estimated inductance and determinewhether the plunger is in one of the open or closed position as afunction of the determined inductance of the solenoid. Further, in someimplementations, the controller can determine, based on the determinedinductance and one or more thresholds, whether the solenoid is in anunknown position between the open and closed positions, and/or whetherthe plunger is removed from the ICM. Similarly, depending on aprecision, some embodiments can further determine an approximatelocation of the plunger between the open and closed positions.

As described above, some embodiments include the filtering and/orisolation circuitry 418. The filtering circuitry can be implemented, atleast in part, to further shape the input stimulus and/or to limit thefrequency content of the input stimulus. Again, the isolation circuitrycan provide isolation for the input stimulus source 410 from otherstages of the PPDC 218 and/or other circuitry. In some embodiments theisolation circuitry comprises a unity-gain amplifier, follower and/orother such buffer devices or circuits. Further, some embodiments includethe gain stage or circuitry 420. The gain stage 420, in someembodiments, includes an operational amplifier (op-amp) coupled betweenthe resistance circuitry 1212 and the A/D converter 416. Theamplification can help reduce sampling errors and/or allow for theutilization of a greater or full dynamic range of the A/D converter 416,the sampling circuitry and the controller. The amplification, in someimplementation, provides an increased sample range of the samplingcircuitry allowing a utilization of a greater number of bits todigitally represent the sampled signal and/or use of a greater dynamicrange of the controller than available without the gain stage.

As one example, a 5V input stimulus can be applied to the solenoid witha duration of 10 μs. The resistance circuitry 1212 can comprise one ormore resistors establishing a resistance of 100Ω. If a voltagemeasurement of 193 mV is measured across the resistance circuitry inresponse to the pulse input stimulus, an estimated current of 1.93 mA iscalculated (193 mA/100Ω). Using the duration of 10 μs, the estimatedchange in current over time (di/dt) is calculated to be 193 A/s (1.93mA/10 μs). The estimated inductance of the solenoid in response to theinput stimulus can then be calculated (L=5V/(193 A/s)) to be 25.9 mH.Based on the calculated inductance the controller can determine whetherthe plunger is in the open or closed position. For example, a thresholdof 25.0 mH can be set as a closed position threshold corresponding to aknown inductance of 26 mH when the plunger is in the closed position.Accordingly, the controller can identify based on the calculated 25.9 mHinductance that the plunger is in the closed position.

As a further example, if a voltage of 265 mV is measured across theresistance circuitry 1212 having the resistance of 100Ω in response to a5V pulse input stimulus having a 10 μs duration applied to the solenoid,an estimated current through the solenoid can be calculated as 2.65 mA(265 mV/100Ω). The change in current over time can be estimated as 265A/s (2.65 mA/10 us). The estimated inductance of the solenoid 310 can becalculated to be 18.9 (L=5V/(265 A/s)). If a threshold of 20.5 mH is setas an open position threshold corresponding to a known inductance of18.5 mH when the plunger is in the open position, the controller canidentify based on the calculated 18.9 mH inductance that the plunger isin the open position. Other thresholds can be defined and used todetermine other locations of the plunger and/or more precision inidentifying a position of the plunger.

FIG. 13 shows a circuit diagram of exemplary circuitry or a systemcomprising a PPDC 218, in accordance with some embodiments. The inputstimulus source 410 injects the input stimulus through the first half ofthe H-bridge switching circuitry 712 that directs the input stimulus toa first terminal of the solenoid 310. A resistance circuitry 1212 iscoupled with the second terminal of the solenoid. The second half of theH-bridge circuitry 714 also couples with the second terminal of thesolenoid and/or the resistance circuitry couples with the solenoidthrough the second half of the H-bridge circuitry 714. In someembodiments, the H-bridge circuitry 712, 714 comprises two sets of backto back MOSFETs on both sides of the solenoid 310.

In some embodiments, the resistance circuitry 1212 comprises one or moreresistors 1312 providing the resistance for the resistance circuitry. Aswitching circuitry or resistance circuitry switch 1314 further couplesin parallel with the resistor 1312. A switching control signal 1316controls the resistance circuitry switch 1314 dictating whether thecurrent flows through the resistance circuitry 1212. In someembodiments, the controller 214 and/or the power control and switchingcircuitry 216 deliver the switching control signal 1316. In associationwith the input stimulus, the resistance circuitry switch 1314 isactivated, and current passing through the solenoid induced by the inputstimulus is directed through the resistor 1312. Further, in someembodiments the resistance circuitry switch 1314 comprises one or moretransistors, such as a MOSFET transistor with the switching controlsignal 1316 coupled with the gate of the transistor.

The switching control signal 1316 activates the resistance circuitryswitch 1314 directing the current from the solenoid through the resistor1312. In some embodiments, the resistance circuitry switch 1314 providesa lower impedance path to ground than the resistor 1312 such thatcurrent passing through the solenoid when a plunger drive signal isapplied to the solenoid is directed to ground instead of passing throughthe resistor 1312. Accordingly, in some embodiments, the activation anddeactivation of the resistance circuitry switch 1314, in associationwith the application of the input stimulus, selectively couples theresistor 1312 with the second terminal of the solenoid.

When attempting to determine a location of the plunger relative to thesolenoid, the switching control signal 1316 induces the resistanceswitching circuitry to direct the current through the resistor 1312(e.g., by opening the current path to ground such that the currentpasses through the resistor 1312). The activation or opening of theresistance circuitry switch 1314 is controlled in accordance with theapplication input stimulus. As such, the current path through thesolenoid as a result of the input stimulus is rerouted through theresistor 1312.

The sampling and/or control circuitry 414 couples with the resistor 1312of the resistance circuitry 1212 and the one or more voltagemeasurements across the resistor 1312 can be taken in response to theinput stimulus being applied to the solenoid. As described above, someembodiments optionally include a gain stage that couples between theresistance circuitry and the sampling circuitry. The gain stage isconfigured to amplify the voltage signal across the resistancecircuitry, which effectively increases a dynamic range of the samplingcircuitry allowing a utilization of a greater number of bits todigitally represent the sampled one or more voltage measurements.

In some embodiments, the one or more voltage measurements are taken at atime proximate an end of the input stimulus (e.g., at approximately thefalling edge of a pulse input stimulus), while in other implementationssome or all of the voltage measurements are taken while the inputstimulus is applied to the solenoid. The current through the solenoid310 is not measured. Instead, the voltage across the resistor 1312 ismeasured and used to determine the inductance as a function of the inputstimulus. Further, in some embodiments, multiple voltage measures aretaken and/or sampled over time and one or more of these measurements arecombined, such as summed, averaged or other such combination, and thecooperated results are used in determining the inductance of thesolenoid to determine a location of the plunger. For example, thecontroller and/or control circuitry can be configured to receivemultiple voltage measurements, cooperate the multiple voltagemeasurements and calculate a cooperative measurement that is evaluatedrelative to one or more thresholds.

Based on the one or more measured voltages across the resistor 1212, theinductance of the solenoid is determined. The controller can evaluatethe determined inductance to identify whether the plunger is in the openor closed position (or an undetermined position or removed from thesolenoid assembly). For example, in some embodiments, the determinedinductance is evaluated relative to a first inductance threshold (e.g.,a closed position inductance threshold), and a location of the plungeris determine as a function of a relationship between the determinedinductance of the solenoid and the first inductance threshold (e.g.,determined inductance is greater than a closed position inductancethreshold corresponding to the plunger being in the closed position).Similarly, the determined inductances can be evaluated relative to asecond known inductance threshold (e.g., an open position inductancethreshold) to determine whether the plunger is in the open position as afunction of a relationship between the determined inductance of thesolenoid and the second known inductance threshold (e.g., determinedinductance is less than an open position inductance thresholdcorresponding to the plunger being in the open position).

Still further, some embodiments determine whether the plunger is removedfrom the solenoid by evaluating the determined inductance relative to athird threshold corresponding to an expected inductance when thesolenoid is removed. Some embodiments further evaluate the determinedinductance to identify that the plunger is in an undetermined position.For example, an undetermined position may be identified as the result ofthe relationship between the determined inductance of the solenoid andopen position inductance threshold and the result of the relationshipbetween the determined inductance of the solenoid and the closedposition inductance threshold (e.g., determined inductance is between anopen position inductance threshold and a closed position inductancethreshold). In some implementations, the plunger position detectioncircuitry of FIG. 13 provides circuitry that has a reduced componentcount over the circuitry of FIG. 8. Additionally, the electrical current(i.e., current draw) may be reduced in the circuitry of FIG. 13 overthat of FIG. 8, and the time to obtain the voltage measurements may bereduced.

FIG. 14 shows a graphical representation of voltage measurements takenacross the resistance circuitry 1212 in response to a pulse inputstimulus applied to the solenoid, in accordance with some embodiments.The graph shows a first plot of voltage measurements 1412 of asimulation when the plunger is in the closed position, and shows asecond plot of voltage measurements 1414 of a simulation when theplunger is in the open position. FIG. 15 shows a graphicalrepresentation of a corresponding current 1512 through the solenoid whenthe plunger is the closed position calculated based on the closedposition voltage measurements 1412, and a graph of a correspondingcurrent 1514 through the solenoid when the plunger is in the openposition calculated based on the open position voltage measurements1414.

FIG. 16 illustrates graphical representations of current passing througha solenoid 310 in response to a pulse input stimulus having a 10 usduration. A first plot 1612 shows the current through the solenoid whenthe plunger is in the closed position while the second plot 1614 showsthe current through the solenoid when the plunger in the open position.FIG. 17 shows graphical representations of voltage across the resistancecircuitry 1212 obtained through sample-and-hold circuitry of an A/Dconverter 416 at a time 10 us after the pulse input stimulus isinitially applied to the solenoid. A first plot 1712 shows the voltagewhen the plunger is in the closed position while the second plot 1714shows the voltage measured when the plunger is in the open position. Insome embodiments, the one or more voltage measurements are sampled atthe controller 214 (e.g., a microcontroller). For example, the graphicalrepresentation of FIG. 17 provides a graph representing the sampling andholding at an A/D converter of the controller or in communication withthe controller.

FIG. 18 shows a simplified flow diagram of an exemplary process 1810, inaccordance with some embodiments, of determining a location of a plungerrelative to a solenoid based on an estimated inductance determined froma measured voltage. In step 1812, an input stimulus is generated andapplied to a first terminal of a solenoid (e.g., the controller 214causes the input stimulus to be generated from the controller and/oractivates a separate input stimulus source). Typically, the inputstimulus is applied to the solenoid while the plunger drive signal isnot being applied to the solenoid. Further, the input stimulus typicallydoes not cause the plunger to change positions.

In step 1814, one or more voltage measurements are taken across aresistive load that is cooperated with the solenoid in response to theinput stimulus. In some embodiments, the controller activates theswitching circuitry, in response to the input stimulus being applied tothe solenoid, to direct current passing through the inductor to theresistive load, and activates the sampling circuitry to take the one ormore voltage measurements across the one or more resistors 1312 of theresistance circuitry 1212 while the current is directed to the resistiveload. In some embodiments, the one or more voltage measurements aretaken at a time proximate an end of the input stimulus (e.g., atapproximately the falling edge of a pulse input stimulus), in otherimplementations some or all of the voltage measurements are taken whilethe input stimulus is applied to the solenoid, while in otherimplementations, some or all of the measurements are taken a delayperiod following the application of the input stimulus.

In step 1816, a current through the resistive load is determined as afunction of the one or more voltage measurements. As described above,some embodiments calculate an estimated change in current over time as afunction of the determined current through the resistive load and aknown or determined pulse duration of the input stimulus. In step 1818,an estimated inductance of the solenoid is determined as a function ofthe determined current and a timing of the input stimulus. Again, forexample, the duration of a pulse input stimulus may be known and used incalculating the estimated inductance of the solenoid 310 (e.g., theduration of at least a portion of an input stimulus (e.g., a half-cycle)can be used to calculate a change in current over time that in turn isused to estimate an inductance of the solenoid). In many embodiments,the estimated inductance is determined without measuring a current, andinstead is calculated based on the measured voltage across theresistance circuitry 1212. Other embodiments, however, may additionallyor alternatively take one or more current measurements and calculate anestimated inductance of the solenoid at least in part based on themeasured current.

In step 1820, the determined inductance is evaluated. Typically, thedetermined inductances is evaluated relative to one or more inductancethresholds. In step 1822, it is determined whether the plunger is theopen or closed positions as a function of a relationship between thedetermined inductance of the solenoid and the one or more inductancethresholds. For example, the determined inductance can be evaluatedrelative to a closed position inductance threshold and/or an openposition inductance threshold. Based on the resulting relationship, itcan be determined whether the plunger is in an open or closed position.Some embodiments are further configured to identify that the plunger isin an undetermined position as a result of both the relationship betweenthe determined inductance of the solenoid and the first inductancethreshold and the relationship between the determined inductance of thesolenoid and the second inductance threshold. Similarly, someembodiments are configured to determine whether the plunger is removedfrom the solenoid (e.g., based on a third inductance threshold), and/ordetermine a location of the plunger between the open and closedpositions (e.g., based on the relationship of the determined inductanceto one or more thresholds and/or at table of expected inductancevalues). Still other embodiments utilize additional thresholds, tablesand/or precision measurements in determining a location of the plungerwhen between the open and closed positions.

In other embodiments, multiple voltage measurements and/or multiplecurrent measurements are taken at multiple times in response to theinput stimulus being applied to the solenoid. A slope of the resultingmeasurements can be calculated and used to determine the position of theplunger.

Some embodiments are additionally configured to determine whether theplunger is stuck in a fixed position and/or not operating as intended.FIG. 19 illustrates a simplified flow diagram of an exemplary process1910 of confirming a location of the plunger and/or determining whetherthe plunger is stuck or otherwise malfunctioning in accordance with someembodiments.

In step 1912, the plunger activation circuitry is triggered to inject aplunger drive signal intending to force the plunger 312 to a predefinedposition. For example, the plunger drive signal can be induced with theintent of force the plunger to be in the closed position. This inducedplunger drive signal can be specifically generated to determine whetherthe plunger is operating effectively and/or is in a stuck condition, canbe injected as part of implementing an irrigation schedule (e.g., anirrigation schedule instructs that irrigation is complete for a givenarea corresponding to a valve coupled with the plunger), can be injectedas part of a system set-up or preset (e.g., flowing an installation ofan irrigation valve 110, multiple irrigation valves, an ICM 108, anirrigation controller 112, establishing a communication with a centralcontroller 102, and/or the installation or set-up of other relevantcomponents of an irrigation system), can be part of an irrigationinitialization (e.g., force valves to be in known states prior toinitiating an irrigation schedule), or other such reasons.

In step 1914, a location of the plunger is determined. In determiningthe location, any one of the above described embodiments or otherembodiments can be used to determine the location. For example, someembodiments inject an input stimulus, take one or move voltagemeasurements across the solenoid and evaluate those one or more voltagemeasurements to determine a location of the plunger (e.g., compare theone or more voltage measurements or a cooperation of the voltagemeasurements relative to one or more thresholds, evaluate an amplitudeof a modulation of the input stimulus relative to one or morethresholds, determine whether a resonant response is generated and/or adegree of resonant response in response to the input stimulus, or othersuch evaluations or combinations of such evaluations). Other embodimentsapply an input stimulus and take one or more voltage measurements of thevoltage across a load resistance, calculate an estimated inductance ofthe solenoid from a voltage measurement (or one or more of the voltagemeasurements when multiple voltage measurements are taken), and comparethe calculated inductance to one or more inductance thresholds todetermine a location of the plunger.

In step 1916, it is determined based on the determined location of theplunger whether the plunger is stuck and/or operating correctly. In someembodiments, the plunger is identified as being stuck or experiencing amalfunction when the determined location of the plunger is not in thepredetermined position or within a predetermine range of the positioninto which the plunger drive signal intended to force the plunger.Subsequent retesting of the plunger movement may be taken before anerror is reported, other action is taken and/or action is recommended tobe taken. In some embodiments, the controller 214 initiates theconfirmation of the location of the plunger. This initiation may resultin response to instructions from the central controller 102 or asatellite irrigation controller 112, may be part of an irrigationschedule, may be part of a predefined procedure, or the like. Upondetermining the plunger is not responding accurately and/or is notmoving to the predefined location, the controller 214 can, in someembodiments, repeat the process 1910 one or more times in attempts toconfirm the erroneous location of the plunger, cause the plunger todislodge from a stuck position, or the like.

The controller 214 can additionally or alternatively issue anotification, alter or warning (e.g., cause the illumination of awarning light, LED, etc. in the ICM 108, ICI 104, satellite irrigationcontroller 112, or the like; send a communication to the centralcontroller 102, an irrigation controller 112, a portable device (e.g.,wireless transceiver, smart phone, etc.); cause an alert or warning tobe displayed on a user display panel of the ICM, satellite irrigationcontroller, ICI, central controller, or the like or combinationsthereof; or other such actions or combinations of such actions). Othernotifications can additionally or alternatively be issued. For example,the central irrigation controller 102 can send a communication (e.g.,email, text message, facsimile, and/or other such communications),trigger a warning or alert (e.g., on a user interface of the centralcontroller 102, an Internet accessed user interface to the centralcontroller, through an application (commonly referred to as an APP) on aportable device (e.g., smart phone, tablet, etc.), or other such alter),and/or other such notifications. Further, the controller 214, satelliteirrigation controller and/or the central controller 102 may take furtheraction in response to the detection that the plunger is stuck ormalfunctioning, such as repeatedly trying to force the plunger to adesired position (e.g., closed position), trigger another valve (e.g., amaster valve), inhibit further implementation of an irrigation schedule,or other such action or combinations of such action.

As introduced above with respect to FIG. 2, some embodiments includeboost circuitry 222. The boost circuitry 222 is configured to allow theICM 108 or other valve control device to operate in low line conditionsand still have enough energy to operate and control the positioning ofthe plunger (and when relevant, plunger position detection circuitry).In some embodiments, the boost circuitry 222 is configured to enhancevoltage from the multi-wire path 106. Again, multiple ICMs 108 aretypically coupled at various locations along the length of themulti-wire path 106 and derive operational power from, for example, anAC waveform received via the multi-wire path 106. Because of thepotential lengths of the multi-wire paths, the amplitude of the ACwaveform is often less further from the ICI 104 or other source of theAC waveform (e.g., at the end of the multi-wire path) than closer to theICI 104. In some instances, the voltage on the multi-wire path at one ormore ICMs is below a threshold and insufficient to ensure effectivevoltage to open or close corresponding solenoid controlled valves. Theboost circuitry can optionally be included in an ICM (or other relevantdevice deriving power over a multi-wire path) and be activated inresponse to detecting that voltage on the multi-wire path is below athreshold to release additional locally stored up energy to effectivelymove the plunger to closed or open positions, and thus effectivelyclosing and opening a corresponding irrigation valve 110.

FIG. 20 illustrates a simplified block diagram of exemplary boostcircuitry 222 in accordance with some embodiment. The boost circuitry222 includes a power or voltage source 2010, one or more boost or powerinductors 2012, charge storage devices or circuitry 2014, a switchcontrol signal source 2016 and switching circuitry 2018. Someembodiments optionally include current control circuitry 2022, 2023, oneor more snubber circuitry 2024, 2026, safety or fail-safe circuitry2030, and/or other such circuitry or combinations thereof.

The voltage source 2010 typically couples with and/or is the multi-wirepath 106 with which the ICM 108 is coupled. In some embodiments,multiple terminals (e.g., terminals of the ICM) electrically couple withthe multi-wire path. As such, the voltage source obtains power from thetwo wire path and is substantially the same as and/or is dependent onthe voltage and/or power levels on the multi-wire path 106 at thelocation along the multi-wire path where the ICM is coupled. In someembodiments, the voltage source 2010 can be AC or DC, and can besupplied externally or internally to the boost circuitry 222. In anexemplary embodiment, the voltage source 2010 originates from theirrigation system (e.g. the ICM) that deploys the solenoid circuitry220, which electrically is previous to the boost circuitry 222. In someembodiments, the voltage source comprises a rectifier that converts aninput AC signal to DC.

The charge storage circuitry 2014 is configured to hold an electricalcharge and to discharge at a later time to deliver a plunger drivesignal. For example, the charge storage circuitry can include one ormore capacitors, rechargeable batteries, super capacitors, or the likeor combinations thereof. Further, the charge storage circuitry isconfigured to cyclically hold charge and then discharge repeatedly overlarger numbers of cycles, and typically for a life of the ICM, withoutadversely affecting the performance of the charge storage circuitry 2014over time. In some embodiment, the charge storage circuitry comprises anetwork of capacitors. Further, some embodiments include a valve-oncharge storage circuitry and a valve-off charge storage circuitry.

In operation, the charge storage circuitry 2014 stores voltage receivedfrom the voltage source 2010. Accordingly, the charge storage circuitrystores a voltage that is at least initially dependent on the voltage ofthe multi-wire path. Again, the plunger drive signal generated withinthe ICM has a threshold voltage in order to achieve a sufficientmagnetic field and/or magnetic forces induced through the solenoid toeffectively move the plunger between the open and closed positions. Insome embodiments, the controller 214 provides boost or power controlcircuitry (or, in some implementations, a separate boost controlcircuitry (not shown) is included), and is configured to monitor thevoltage on the multi-wire path 106. In some embodiments, this voltagelevel is monitored by monitoring the voltage stored on the chargestorage circuitry 2014. In other embodiments, the charge storagecircuitry 2014 comprises voltage monitoring circuitry that monitors avoltage stored in the charge storage circuitry and can report theresults to the controller 214.

In those instances where the controller 214 determines that the voltageon the multi-wire path is below a first plunger drive signal threshold,the controller 214 activates the switch control signal source 2016 thatdelivers a switch control signal to the switching circuitry 2018. Insome embodiments, the switch control signal is an alternating signalthat sequentially and repeatedly activates and deactivates or otherwisetriggers the switching circuitry 2018. For example, in someimplementations, the switch control signal has a known duty cycle,frequency, pulse width and/or other such known characteristics toachieve the desired alternating activation and deactivation, as well asmaintaining the switch in the desired active state or deactivated statefor desired periods of time to achieve desired changes in current flowthrough the one or more power inductors 2012. Some embodiments utilize apulse width modulated (PWM) signal that is used to control the switchingcircuitry.

In response to the switch control signal, the switching circuitry 2018repeatedly turns on and turns off alternately inducing and halting acurrent through the one or more power inductors 2012. The one or morepower inductors 2012 are cooperated with the switching circuitry 2018and store energy in the induced magnetic field in response to thetransition of the switching circuitry between on (current conducting)and off states. When the switching circuitry transitions to an off statestopping the current flow, the stored energy in the one or more powerinductors is released to energize and/or charge the charge storagecircuitry 2014. In response to the changing current as a function oftime (di/dt) through the one or more power inductors 2012, a boostvoltage is temporarily established across the one or more powerinductors (V=di/dt*L) that is greater than the voltage delivered by thevoltage source 2010. This temporary boost voltage is stored in thecharge storage circuitry 2014 in additional to the voltage alreadystored as a result of the voltage on the multi-wire path. For example,the control circuitry can be configured to generate a PWM signal that isapplied to the switching circuitry to implement sequential triggering ofthe switching circuitry in response to the PWM signal to induce thechange in current over time through the one or more power inductors,which in some implementations corresponds to a frequency of the PWMsignal.

As described above, the switch control signal turns on and off theswitching circuitry activating and deactivating the switching circuitryinducing the boost voltage. The switch control signal from the switchcontrol signal source 2016 provides the switching control signal causingthe transition of the switching circuitry between on (i.e., currentconducting) and off (i.e., non-conducting), which consequently modulatesthe storing and releasing of energy through the one or more powerinductors 2012. When the one or more power inductors release energy, theequivalent electronic circuit that is formed comprises two sources inseries (i.e., the voltage source 2010 and the voltage potential acrossthe one or more power inductors). The increased energy from the one ormore power inductors results in an increase in the voltage level (theincremental boost voltage) at the charge storage circuitry 2014 that ishigher than the voltage source 2010 boosting the voltage level of thevoltage source.

The charge storage circuitry 2014 is charged from voltage source 2010and the boost voltage to increase the voltage stored on the chargestorage circuitry. When the voltage across the charge storage circuitryreaches a threshold level, for example, the first plunger drive signalthreshold, the controller 214 can deactivate the control signal source2016 stopping the switch control signal from activating and deactivatingthe switching circuitry 2018. Accordingly, the boost circuitry 222 isconfigured to increase a voltage stored on the charge storage circuitry2014 above a predefined threshold allowing the ICM to boost the locallystored voltage to allow effective opening and/or closing of acorresponding irrigation valve even when the voltage on the multi-wirepath 106 is below a threshold voltage level sufficient to close and/oropen the valve.

As introduced above, some embodiments optionally include one or morecurrent control circuitry 2022, 2023. A first or source current controlcircuitry 2022 can be incorporated into the boost circuitry 222 coupledbetween the voltage source 2010 and the one or more power inductors2012, and be configured to conduct from the voltage source 2010 towardthe one or more power inductors 2012 while inhibiting or preventingcurrent from being conducted in the opposite direction (i.e. from theone or more power inductor toward the voltage source). In someembodiments, the source current control circuitry 2022 acts as aprotection mechanism that allows the one or more power inductors 2012 toenergize the charge storage circuitry 2014 while not energizing anoutput impedance network that may be associated with the voltage source2010.

Some embodiments may optionally include a second or output currentcontrol circuitry 2023 coupled between the one or more power inductors2012 and the charge storage circuitry 2014. Similar to the sourcecurrent control circuitry 2022, the output current control circuitry2023 can be configured to conduct from the one or more power inductors2012 toward the charge storage circuitry 2014, but does not conduct inthe opposite direction (i.e., from the charge storage circuitry towardto the one or more power inductors). Again the output current controlcircuitry 2023 can operate as a protection mechanism that does not allowthe charge storage circuitry to naturally discharge through an undesiredelectrical path, particularly through the one or more power indictorsand the switching circuitry 2018 when the switching circuitry isactivated (e.g., “on”).

Further, some embodiments include an optional fail-safe circuitry 2030that provide protection of the one or more power inductors 2012, chargestorage circuitry and/or the voltage source 2010 from a potential shortcircuit condition by establishing an off condition. In someimplementation, the fail-safe circuitry limits or prevents the chargestorage circuitry 2014 once charged from inadvertently discharging as aresult of a failure, for example, of the switch control signal source2016. In some implementations, should the switch control signal source2016 failed, for instance, in a mode that forces the switching circuitry2018 to an “on” state, the voltage source 2010 could potentially beconstantly connected to a reference ground, resulting in a “shortcircuit” condition. The short circuit condition may allow high currentto be conducted through the one or more power inductors, which couldresult in a permanent failure of the one or more power inductors and/orthe voltage source 2010. The fail-safe circuitry 2030, however, ensuresan “off” state of the switching circuitry 2018 to prevent the shortcircuit condition.

Still further, some embodiments include emission protection circuitrythat limit or reduce electromagnetic interference (EMI). For example,some embodiments optionally include emission protection circuitrycomprising one or more snubber circuitry 2024, 2026. The snubbercircuitry can be configured to reduce noise in the switching and/or canmodify the frequency response of the boost circuitry 222 in order tomanage. Some embodiments additionally or alternatively limit and/oreliminate electromagnetic interference (EMI) that may result, forexample, from undesired oscillations produced by the operation of theboost circuitry.

FIG. 21 shows a simplified flow diagram of an exemplary process 2110, inaccordance with some embodiments, of boosting the voltage from themulti-wire path in controlling the movement of the plunger between theopen and closed positions, thus, controlling the opening and closing ofthe irrigation valve. In step 2112, it is determined at the ICM 108, orother such an irrigation valve control circuitry, whether a voltage on amulti-wire path has a known relationship with a boost threshold. Forexample, it can be determined whether the voltage is less than a boostthreshold. Again, this determination may be determined by the controller214 of the ICM, a separate boost circuitry controller or other suchcontroller. In some embodiments, this voltage on the multi-wire path isdetermined based on a voltage measured and/or monitored at the one ormore charge storage circuitry 2014. Again, the ICM obtains power fromthe multi-wire path and uses that power in part to move the plunger 312to open and close the corresponding irrigation valve.

In step 2114, the boost circuitry is activated in response todetermining that the voltage on the multi-wire path is less than theboost threshold. In step 2116, a boost voltage is generated, through theboost circuitry, to increase the voltage stored by the one or morecharge storage circuitry 2014 to be greater than the voltage on themulti-wire path. In some embodiments the switch control signalalternately induces and halts current flow through the one or more powerinductors 2012, which in turn generates the incremental boost voltagethat is accumulated on the charge storage circuitry 2014.

In step 2118, the one or more charge storage circuitry 2014 are charged,through the boost voltage, to a desire voltage that is greater than thevoltage on the multi-wire path in response to the boost voltage.Accordingly, in some embodiments where the charge storage circuitry arecharged, steps 2116 and 2118 may be part of a loop to repeatedlygenerate the boost voltage that is accumulated over time on the chargestorage circuitry. Typically, the charge storage circuitry is charged toat least the boost threshold. Further, in some embodiments, the boostthreshold is sufficient to at least ensure that the plunger can be movedto a closed position to close the corresponding valve and preventfurther water distribution through the valve. Some embodiments considermore than one threshold. For example, there may be a closing boostthreshold corresponding to a voltage to move the plunger to a closedposition, and an open boost threshold corresponding to a voltage to movethe plunger to an open position. In some instances, the opening andclosing boost thresholds may be different levels.

In step 2120, at least one of the one or more charge storage circuitry2014 is discharged to provide the plunger drive signal that drives acurrent through the solenoid in controlling movement of the plunger tocause the plunger to be in a desired position (e.g., change positionsfrom the open to the closed position, or vice versa). Again, in someembodiments, the controller further dictates whether the plunger isbeing moved to the open or closed position by controlling a direction ofcurrent flow through the solenoid (e.g., through the power control andswitching circuitry 216). The plunger is cooperated with and/or coupledwith a portion of an irrigation valve, where typically water is allowedto pass through the valve when the plunger is in an open position andwater is prevented from passing the valve when the plunger is in aclosed position.

In some embodiments, one or more irrigation schedules provide controlover irrigation and/or can be interpreted as an orchestration on when,for how long, for how many cycles, etc., one or more valves (e.g., aparticular rotor's valve) will be turned on or off such that water isdelivered to a certain area, and typically attempts to controlirrigation without exceeding the entire irrigation system capacity toproperly supply water (e.g., at a certain specified pressure and flowrate). Further, in some implementations, during such control, commandsmay be sent to the one or more ICMs 108, 116 to actuate correspondingplungers (to turn on or off the corresponding one or more valvesassociated with the ICM). Typically, these command (e.g., on or off)that are executed causes the charge storage circuitry 2014 to issue theplunger drive signal (e.g., capacitors discharge such that current flowsthough the solenoid). In some embodiments, before the execution of anirrigation command, the controller 214 checks to determine whether thevoltage on the multi-wire path 106 and/or stored on the one more chargestorage circuitry 2014 meets one or more certain levels (e.g., a plungerON threshold) that is adequate for a reliable execution of theirrigation command.

In some implementations, the boost circuitry 222 is configured tooperate when a voltage threshold is not met or until the one or morecharge storage circuitry 2014 are charged to or above the voltagethreshold. The controller 214, in some instances, can periodically(e.g., multiple times per minute, multiple times per second (e.g., 10times per second), or other such interval) measure the voltage of at thecharge storage circuitry 2014 and/or the multi-wire path, determine thevoltage threshold is met, and if not turn on activate the boostcircuitry 222 until the threshold is met. Further, in manyimplementations, even when irrigation commands are not being executed,the charge storage circuitry may discharge slowly due to the currentdraw of the power distribution 212 and/or other circuitry connected toit. Similarly, in the case where the voltage level on the multi-wirepath 210 is high enough to not require boosting, in some embodiments thevoltage level on the charge storage circuitry is adequately maintainedbecause the charge storage circuitry continue to charge as voltage isdrained of by other circuit connected to it.

Additionally, in some embodiments, the boost circuitry 222 may beconfigured to automatically activate to recharge the charge storagecircuitry in response a drop in the voltage level of charge storagecircuitry below the threshold in response to the charge storagecircuitry discharging to deliver the plunger drive signal in response toan irrigation command. This automatic activation in response todischarge may be limited to when the voltage on the multi-wire path 210is below the threshold, or may be configured to activate regardless ofthe voltage on the multi-wire path. Typically, the rate of dischargethrough the power distribution circuitry 212 and/or other circuitryconnected to it is slow relative to how fast the boost circuitry iscapable of boosting the voltage stored on the charge storage circuitryback to a level at or above the threshold. In some embodiments, thecontroller 214 may further be programmed and/or otherwise configured todetect an irrigation command is to be executed and activate the boostcircuitry in response to the irrigation command activation. Additionallyor alternatively, the controller 214 can be programmed and/or configuredsuch that when an irrigation command is executed the controller candiscriminate between the voltage drop in response to implementing theirrigation command and other occurrences when the voltage drops below aboost threshold.

FIG. 22 depicts a simplified circuit diagram of exemplary boostcircuitry 222 in accordance with some embodiments. The boost circuitry222, in this embodiment, includes the voltage source 2010 coupled withone or more boost or power inductors 2012 that couple with a firstcharge storage circuitry 2210 and a second charge storage circuitry2212. In some embodiments, the first charge storage circuitry 2210includes one or more capacitors and the second charge storage circuitry2212 includes one or more capacitors. Typically, the boost circuitry isconfigured to charge both the first charge storage circuitry and thesecond charge storage circuitry increasing the stored voltage. Inoperation, at least one and typically both the first and second chargestorage circuitry 2210, 2212 are discharged (e.g., through the H-bridgeswitching circuitry 712, 714) to generate the plunger drive signalconfigured to move the plunger to a desired position (e.g., open orclosed position). In some embodiments, the controller 214 tracks one orboth VON 2214 and VOFF 2216 in determining whether to activate the boostcircuitry 222 to further charge the first and/or second charge storagecircuitry.

The switching circuitry 2018 is coupled between the one or more powerinductors 2012 and the first and second charge storage circuitry. Inthis embodiment, the switching circuitry comprises a transistor (e.g.,MOSFET transistor, insulated-gate bipolar transistor (IGBT), etc.) withthe switch control signal coupled with the gate of the transistor. Theswitch control signal activates and deactivates the transistor toinclude the current flow through the one or more power inductors 2012and through the transistor resulting in repeated generation of the boostvoltage that is stored in one or both of the first and second chargestorage circuitry 2210, 2212.

The one or more power inductors 2012 are coupled with the switchingcircuitry 2018 and are configured to store energy through inducedmagnetic fields when the transistor is switched “on” causing currentchange through the one or more power inductors 2012 (e.g., through theswitching circuitry 2018 to a reference ground). When the transistor isswitched “off” the stored energy in the one or more power inductors 2012is released charging the first and second charge storage circuitry 2210,2212. It is noted that more than one reference ground may be implementedsimultaneously within the boost circuitry 222 (and/or within the ICM 108or circuitry within the ICM), for example, to in part provide someisolation for portions of the boost circuitry 222 (and/or othercircuitry when relevant).

As introduced above, in some embodiments, the switch control signal caninclude a PWM signal supplied by the switch control signal source 2016.Further, in some embodiments, the switch control signal source 2016 iscontrolled by and/or implemented as part of the controller 214 (e.g., amicrocontroller of the ICM through which the controller 214 isimplemented). The switch control source can be configured to supplies avoltage waveform that oscillates at a fixed frequency with a fixduty-cycle (e.g., a square wave, sine wave, etc.). For example, theswitch control signal can be a PWM signal with a 1-50% duty cycle. Insome embodiments, the duty cycle is dependent on a frequency of theswitch control signal. Further, in some implementation, however, theswitch control signal has a variable frequency and/or duty cycle.

Further, the controller is configured to automatically activate theswitch control signal source 2016 and/or generate the switch controlsignal in response to notification and/or determining that the voltageon the multi-wire path 106 and/or the charge stored on one or both ofthe first and/or second charge storage circuitry 2210, 2212 are belowone or more voltage level thresholds (e.g., plunger movement threshold).In some embodiments, the switch control signal is generated (e.g., as aPWM signal) and is not monitored or adjusted, but merely applied toinduce the generation of the boost voltage and is not varied relative tocharacteristics of an input.

Some embodiments optionally include a first or source current controlcircuitry 2022 comprising a source diode 2220. The source diode 2220 isforward biased such that it conducts current from the voltage source2010 towards the one or more power inductors 2012, while inhibitingcurrent from being conducted in the opposite direction (i.e. from thepower inductor to the voltage source or other portion of the circuitry).Accordingly, the source diode 2220 prevents the boost voltage from beingdrawn away from the one or more charge storage circuitry.

Further, the embodiment depicted in FIG. 22 optionally includes a secondor output current control circuitry 2023 that includes a first chargestorage diode 2222 and/or a second charge storage diode 2224. Similar tothe source diode, the first and second charge storage diodes 2222, 2224are forward-biased such that they conduct current from the one or morepower inductors towards the first and/or second charge storage circuitry2210, 2212, while inhibiting current from being conducted in theopposite direction (i.e., from the charge storage circuitry to the oneor more power inductors and/or the switching circuitry). Further, thefirst and/or second charge storage diodes 2222, 2224 are used asprotection mechanisms that inhibit the charge storage circuitry fromdischarging through the electrical path that is otherwise imposed by theone or more power indictors and/or the switching circuitry 2018 (e.g.,when the transistor is switched “on” to conduct current).

Switching noise may result in response to the repeated switching, and insome implementations the rapidly repeated switching of the switchingcircuitry 2018. Further, this switching noise may cause unwanted EMIbursts. As described above, some embodiments optionally include one ormore snubber or other such protection circuitry 2024, 2026. For example,a first snubber circuitry 2024 can be included in the boost circuitry222 coupled across the first charge storage circuitry 2210. Someembodiments may additionally or alternatively optionally include asecond snubbing circuitry 2026 coupled across the switching circuitry2018. In some embodiments, one or both of the snubber circuitry 2024,2026 can comprise resistor and capacitor connected in series. Again, thesnubber circuitry, in some embodiments, is configured to at least inpart modify the frequency response of the boost circuitry 222 in orderto manage or eliminate electromagnetic interference (EMI) that mayresult from undesired oscillations produced by the operation of theboost circuitry.

Some embodiments further include an enhanced resistance 2230. At leastin part, the enhanced resistance is configured to aid in controlling aspeed of the switching circuitry 2018. In some embodiments, the enhancedresistance has a resistance value of about 5KΩ, while in otherembodiments the resistance may be 20KΩ or more. This enhanced resistancecan, in some embodiments, also help in controlling and/or limiting EMIbursts.

As described above, some embodiments optionally include the fail-safecircuitry 2030. In part, the fail-safe circuitry 2030 helps to controlor assure that once the charge storage circuitry is charged it does notdischarge as a result of a failure on the switch control signal source2016. In some embodiments, the switch control signal source 2016generates the switch control signal oscillates periodically such thatthe switch (e.g., MOSFET transistor) is modulated and periodicallyswitching between “on” and “off” states. If the switch control sourcefails, for instance, as a failure mode constantly drives the switchingcircuitry such that the switching circuitry is constantly operated as anelectronic “on” switch, the voltage source 2010 may be constantlyconnected to the reference ground, which in turn will result in a shortcircuit condition. The short circuit condition may allow high current tobe conducted through the one or more power inductors 2012, which mayresult in permanent failure of the one or more power inductors and/orthe voltage source 2010. In some embodiments, the fail-safe circuitrycomprises a fail-safe capacitance 2232 and parallel coupled resistance2234.

FIG. 23 shows a graphical representation of a switch control signal 2310applied to the switching circuitry 2018 of the boost circuitry, inaccordance with some embodiments. FIG. 24 illustrates a graphicalrepresentation of a change in current 2410 as a function of time throughthe one or more power inductors 2012 in response to the activation ofthe switching circuitry induced by the switch control signal 2310, inaccordance with some embodiments. After a pulse from the switch controlsignal triggers the switching circuitry (e.g., turn off), in someembodiments, the current through the one or more power inductors decays.The voltage on an output side of the one or more power inductors risesto a level in excess of the voltage on the multi-wire path and/or VON2214. For example, in some implementations when the current controlcircuitry 2023 comprises a diode 2222, the voltage at the output side ofthe one or more power inductors is raised to at least VON+V_(D2222).Again, this boost voltage charges the one or more charge storagecircuitry 2014 (e.g., first charge storage circuitry 2210 and a secondcharge storage circuitry 2212).

In some embodiments, a boost rate (V/s) can be determined by the pulsewidth of the switch control signal, a frequency of the switch controlsignal, the line voltage of the multi-wire path and/or the voltage ofthe power source 2010, and an efficiency of the boost circuitry. As anexample, a switch control signal can be applied from the controllerwhere each pulse of the signal provides 50 nC (as defined byAmps=Coulombs/sec.), when the signal has an average of 5 mA/pulse*10 usyielding the 50 nC. With the charge storage circuitry 2014 comprisingcapacitors, Farads are defined as Coulombs/volt. To increase a voltageacross a 440 ufds capacitance, 440 uC is generated. Applying theexemplary switch control signal defined by a 50 nC/pulse*10K pulses persecond yields 500 uC/s. Translating to voltage (500 uC/s*1V/440 uC)yields a boost rate of approximately 1.1V/S. Actual boost rates maydeviate from this example, due for example to efficiency losses. It isfurther noted that the voltage from the voltage source 2010 may alsoaffect an average boost current and thus the resulting boost rate.

Again, some embodiments limit the switching speed or transition rate2312, 2314 of the switching circuitry, which can limit or preventoscillation during switching (e.g., via the one or more power inductors2012, the switching circuitry 2018, and in some instances diodecapacitance) and/or reduce EMI emissions. Further, in some embodiments,with the switching circuitry 2018 comprising a transistor, a gate of thetransistor is capacitively coupled through a fail-safe capacitance 2232with the controller 214 (e.g., microprocessor) to provide protectioncontrol in an off state. Furthermore, some embodiments reduce the speedof the switching circuitry 2018 at least in part with the insertion ofthe enhanced resistance 2230 coupled with the gate. Some implementationstake advantage of inherent gate capacitance of a transistor and createan RC circuit that can in part control and/or result in a reduced and/orrelatively slow rise time of a gate voltage. In some instances, therelatively slow switching speed can result in losses in efficiency.These losses in efficiency, however, are often acceptable because of thecontrol and/or elimination of EMI. Some efficiency can be gained withthe inclusion of the one or more snubber circuitry 2024, 2026 allowing aspeed up of the switching speed.

The boost circuitry 222 depicted in FIG. 22 utilizes the one or morepower inductors 2012 in cooperation with the switching circuitry 2018 togenerate the boost voltage that charges the one or more charge storagecircuitry 2014. Other boost circuitry is alternatively or additionallyutilized in other embodiments. For example, some embodiments utilize atransformer connected to the line side that is configured to step up thevoltage for charge storage circuitry. A full bridge switch mode powersupply (SMPS) may be used where a step up DC/DC converter is configuredas an isolated circuit providing high frequency transformer couplingwhere a secondary provides a higher voltage than the primary. Otherembodiments may include a charge pump, for example, comprising one ormore capacitors connected in parallel with an input capacitor, which arethen switched out to a series configuration to provide twice thevoltage. This switching from parallel to series can be repeated a numberof times transferring charge from the input to the charge storagecircuitry and/or directly to the plunger activation circuitry or as partof the plunger activation circuitry. Other circuitry and/or methods maybe utilized to boost the voltage received from the multi-wire path.

Referring back to FIG. 2, some embodiments include temperature sensingcircuitry 224. The temperature sensing circuitry is configured toprovide information corresponding to measured temperature. Thistemperature information can be used by the controller 214 incompensating for variations in other measured parameters that may beaffected by a current temperature. For example, the voltage across thesolenoid 310 and/or the current flowing through the solenoid can varydepending on a current temperature and/or vary as a function oftemperature.

In some implementations there can be contributing factors that causedifferences in a response to the input stimulus as temperature varies.For example, the winding of the solenoid typically are dependent on aresistance temperature coefficient and/or a permeability temperaturecoefficient. These factors, as well as device to device variations, cancause sufficient variations in operation that some embodiments factorthese potential variations into one or more measurement algorithmsand/or thresholds in attempts to limit and/or prevent false positionreadings.

Accordingly, the controller 214 utilizes the temperature information, insome embodiments, to compensate for these variations. For example, insome implementations, the temperature sensing circuitry is configured toprovide an indication of a current temperature of an environment inwhich the solenoid is positioned. The controller utilizes thistemperature information in evaluating the one or more voltagemeasurements relative to the first threshold. Further, the controllercan adjust one or more thresholds (or utilize alternative thresholds)that are used to determine a location of the plunger 312. In someimplementations the controller is configured to adapt the evaluation ofthe one or more voltage measurements relative to one or more thresholdand/or modify the one or more thresholds as a function of the indicationof the current temperature. Similarly, a threshold of a voltage receivedfrom the multi-wire path and/or a threshold of the voltage stored in thecharge storage circuitry 2014 may be adjusted (or an alternativethreshold used) to ensure that the plunger activation circuitry, powercontrol and switching circuitry 216, charge storage circuitry 2014, andthe like can deliver a plunger drive signal that is sufficient to inducethe desired movement of the plunger 312 relative to the solenoid to movethe plunger to the intended open or closed position.

FIG. 25 shows exemplary graphical representations of measurements(vertical axis) relative to temperature (horizontal axis in Celsius), inaccordance with some embodiments. In some embodiments, therepresentation of the measurements are a decimal numeric system(sometimes referred to as “counts”) of what an A/D converter 416 (e.g.,inside the controller 214) outputs when voltage is measured across thesolenoid in response to, and in some instances during, the execution ofan input stimulus (e.g., a pulse). Further, in some implementations thetemperature sensing circuitry 224 provides temperature information,which in some implementation is measured inside the ICM 108, 116.

A first plot 2512 (solid) is an interpolation utilizing measured data,and a second plot 2514 (dash-line) is the result of a linear curvefitting, showing the plunger detection circuit response over temperaturewhen the plunger is in the open position (i.e., ON with the valve open).A third plot 2516 (solid) is an interpolation utilizing measured data,and a fourth plot 2518 (dash-line) is the result of a linear curvefitting, showing plunger detection circuitry response over temperaturewhen the plunger is in the closed position (i.e., OFF with the valveclosed). In some embodiments, the linear representation of the curvesare determined using the formula: y=m*x+b, where y corresponds to themeasurement counts, m is a slope (calculated from empirical results, andsometimes referred to as a calibration constant), x corresponds to thesensed temperature information, and b is a y-intercept (where the plotscross the vertical axis). In some implementations the m, the slope, isreferred to as a temperature coefficient (e.g., when the slope is zerothere is typically no variation or dependence in temperature).

Further, FIG. 25 also shows an exemplary threshold 2520, in accordancewith some embodiments, between the two plots 2512, 2516, where ameasured voltage above the threshold relative to the temperature may beidentified as the plunger being in the open or ON position, while ameasured voltage below the threshold relative to the temperature may beidentified as the plunger being in the closed or OFF position. Someembodiments include more than one threshold allowing the system toidentify with more precision the location of the plunger, such aswhether the plunger is in a 70% open position, 90% open position, 90%closed position, etc. Accordingly, some embodiments compensate fortemperature variations in accurately identifying a location of theplunger relative to the solenoid.

In some embodiments, the temperature sensing circuitry 224 may beincorporated into a housing 320 of an ICM 108, while in otherembodiments some or all of the temperature sensing circuitry may beimplemented outside the ICM. The temperature sensing circuitry comprisesa temperature sensor that is configured to sense the temperature of anenvironment in which the plunger position detection circuitry 218 isoperated. Accordingly, in some instances, it is beneficial that thetemperature sensor be positioned proximate the PPDC 218 and/or thesolenoid 310. It is noted that in some instances, some or all of theplunger detection circuitry, the solenoid and/or some or all of aninterior of an ICM may be protected from environmental conditionsthrough an encasement within a resin, epoxy or other such pottingmaterial. Accordingly, some embodiments ensure that the temperaturesensor is positioned within the potting material and/or within theenvironment in which the solenoid is positioned so that the temperaturesensed is consistent with a temperature of the relevant components ofthe ICM.

As described above, some embodiments identify a location of the plungerbased on one or more thresholds. For example, in some implementations, aplunger is identified as being in the open position when parameters(e.g., one or more voltage measurements, current measurements,calculated inductance, etc.) has a first predefined relationship withthe threshold (e.g., less than a threshold), and identified as being inthe closed position when the predefined relationship does not exist.Other embodiments consider one or more additional thresholds and/orranges.

Some embodiments are configured to determine a relative location of theplunger along the range of motion of the plunger. Further, the locationcan, in some embodiments, be determined as a proportional location ofthe plunger relative to one of the open and closed positions and a rangeof motion of the plunger. For example, in some implementations, thecontroller can receive and/or calculate theoretical voltage for a fullyon position and a fully off position. Based on the measured voltageand/or cooperated voltage obtained from multiple voltage measurements, aproportional location can be determined or a quality of “on” and “off”.In some implementations, measurements corresponding to the fully “on”and the fully “off” positions can be designated 100% and 0%,respectively, with measurements between corresponding to proportionallyopen or closed. Measurements and/or calculated parameters between the100% and 0% can be evaluated to determine one of a level of how open anda level of how closed, wherein the level of how open and the level ofhow closed are defined by an estimated proportional position of theplunger relative to a range of motion of the plunger and at least one ofa fully open position at a first limit of the range of motion and afully closed position at a second limit of the range of motion.

Some embodiments use one or more temperature measurements and/or one ormore calibration constants, where the calibration constant is the slope‘m’ in the linear representation y=m*x+b. Some embodiments furtherdefine an m_(on) and an m_(off). A proportional location and/or aquality of the position can be determined based on these calibrationconstants. Some embodiments further normalize the calibration constantsto +100 for the “on” position, and −100 for the “off” position.

For example, one or more measurements are taken in response to one ormore input stimulus signals. The temperature sensing circuitry 224 canprovide the controller 214 with temperature information. The controlleris configured to calculate a theoretical P_(ON) value, where the P_(ON)value is a digital representation of one or more voltage measurementstaking by a sampling circuitry (e.g., A/D converter counts)corresponding to the plunger being in the open or “on” position. In someimplementations, P_(ON)=m_(ON)T+b_(ON), based on the application ofy=m*x+b for the ON curve 2514 (e.g., see FIG. 25). Similarly, atheoretical P_(OFF) value is calculated, where P_(OFF)=m_(OFF)T+b_(OFF),which is again based on the application of y=m*x+b. Some embodimentscalculate a normalization scaling (N) defined by N=200/(P_(ON)−P_(OFF)).Further, some embodiments determine or calculate a theoretical midpoint,Midpt=(P_(ON)−P_(OFF))/2. Based on the normalization scaling (N) and themidpoint (Midpt), some embodiments calculate a normalized measurementPing_(norm)=(Ping−Midpt)*N, where in some instances, the controllercauses Ping_(norm) to be sent. So, a result detected based on an inputstimulus that is +100, the controller identifies the plunger is in openor on position (i.e., fully on), while if results are determined to be+80 the plunger is identified as being in in the 80% open position(i.e., 80 on). Alternatively, when results are determined to be −100,the plunger is recognized as being in the fully closed or off position.Some embodiments simply identify the plunger as in the open position,closed position or undetermined (e.g., above 50%=ON, below 50%=OFF, at50%=undetermined).

The methods, techniques, systems, circuitry, devices, services, servers,sources and the like described herein may be utilized, implementedand/or run on many different types of devices, circuitry, systems and/orcombinations thereof. Referring to FIG. 26, there is illustratedcircuitry 2600 that may be used in such implementations, in accordancewith some embodiments. One or more components of the circuitry 2600 maybe used for implementing any system, circuitry, apparatus or devicementioned above or below, or parts of such systems, apparatuses,circuitry or devices, such as for example any of the above or belowmentioned central controller 102, ICI 104, satellite irrigationcontroller 112, ICM 108, 116, front-end and communication circuitry 210,power distribution circuitry 212, controller 214, power control andswitching circuitry 216, PPDC 218, solenoid circuitry 220, boostcircuitry 222, temperature sensing circuitry 224, and/or other suchsystems, circuitry, devices and the like. However, the use of thecircuitry 2600 or any portion thereof is certainly not required.

By way of example, the circuitry 2600 may comprise a controller,microcontroller or processor module 2612, memory 2614, and one or morecommunication links, paths, buses or the like 2616. In someimplementations the controller 2612 and some or all of the memory 2614are cooperated as a single control element or circuitry 2610, such as asingle microprocessor, microcontroller or the like. The controller 2612can be implemented through one or more processors, microprocessors,central processing unit, logic, local digital storage, firmware and/orother control hardware and/or software, and may be used to execute orassist in executing the steps of the methods and techniques describedherein, and control various communications, programs, content, listings,services, interfaces, etc. A power source or supply 2640 is included orcoupled with the circuitry 2600.

Some embodiments optionally include a user interface 2620. The userinterface 2620 can allow a user to interact with the circuitry 2600, andin some implementations receive information through the circuitry. Insome instances, the user interface 2620 includes a display 2622 and/orone or more user inputs 2624, such as a button(s), touch screen, rotarydial(s), remote control, keyboard, mouse, track ball, etc., which can bepart of or wired or wirelessly coupled with the circuitry 2600.

Typically, the circuitry 2600 further includes one or more communicationinterfaces, ports, transceivers 2618 and the like allowing the circuitry2600 to communication with one or more other devices, systems,circuitry, and the like, or combinations thereof. For example, in someimplementations, the one or more communication interfaces ortransceivers 2618 allow the circuitry to communicate over the multi-wirepath, 106. Additionally or alternatively, the one or more transceivers2618 may allow communication over a distributed network, a localnetwork, the Internet, communication link, other networks orcommunication channels with other devices and/or other suchcommunications. Further the transceiver 2618 can be configured forwired, wireless, optical, fiber optical cable or other suchcommunication configurations or combinations of such communications(e.g., wireless communication via one or more antennas 2636). Someembodiments additionally include other input and/or output interfaces2634 that allows the circuitry to couple with and/or communicate withother external devices, systems or the like.

The circuitry 2600 comprises an example of a control and/orprocessor-based system with the controller 2612. Again, the controller2612 can be implemented through one or more processors, controllers,central processing units, logic, software and the like. Further, in someimplementations the controller 2612 may provide multiprocessorfunctionality.

The memory 2614, which can be accessed by the controller 2612, typicallyincludes one or more processor readable and/or computer readable mediaaccessed by at least the controller 2612, and can include volatileand/or nonvolatile media, such as RAM, ROM, EEPROM, flash memory and/orother memory technology. Further, the memory 2614 is shown as internalto the circuitry 2610; however, the memory 2614 can be internal,external or a combination of internal and external memory. The externalmemory can be substantially any relevant memory such as, but not limitedto, one or more of flash memory secure digital (SD) card, universalserial bus (USB) stick or drive, other memory cards, hard drive andother such memory or combinations of such memory. The memory 2614 canstore code, software, executables, scripts, data, programming, programs,irrigation scheduling, sensor data, log or history data, userinformation, or the like, or combinations thereof.

One or more of the embodiments, methods, processes, approaches, and/ortechniques described above or below may be implemented in one or morecomputer programs executable by a processor-based system. By way ofexample, such a processor based system may comprise the processor basedcircuitry 2600, a computer, central irrigation controller, a satelliteirrigation controller, tablet, smart phone, etc. Such a computer programmay be used for executing various steps and/or features of the above orbelow described methods, processes and/or techniques. That is, thecomputer program may be adapted to cause or configure a processor-basedsystem to execute and achieve the functions described above or below.For example, such computer programs may be used for implementing anyembodiment of the above or below described steps, processes ortechniques to identify plunger location, report such plunger location,instruct actions to be taken, implement actions, implement irrigationschedules and/or other such functions or actions. As another example,such computer programs may be used for implementing any type of tool orsimilar utility that uses any one or more of the above or belowdescribed embodiments, methods, processes, approaches, and/ortechniques. In some embodiments, program code modules, loops,subroutines, etc., within the computer program may be used for executingvarious steps and/or features of the above or below described methods,processes and/or techniques. In some embodiments, the computer programmay be stored or embodied on a non-transitory computer readable storageor recording medium or media, such as any of the computer readablestorage or recording medium or media described herein.

Accordingly, some embodiments provide a processor or computer programproduct comprising a medium configured to embody a computer program forinput to a processor or computer and a computer program embodied in themedium configured to cause the processor or computer to perform orexecute steps comprising any one or more of the steps involved in anyone or more of the embodiments, methods, processes, approaches, and/ortechniques described herein. For example, some embodiments provide oneor more computer-readable storage mediums storing one or more computerprograms for use with a computer simulation, the one or more computerprograms configured to cause a computer and/or processor based system toexecute steps comprising: causing an input stimulus to be applied to asolenoid at a time while a plunger drive signal is not being applied tothe solenoid, wherein the solenoid is configured to cooperate with aplunger and to receive the plunger drive signal that induces a magneticfield relative to the solenoid that causes the plunger to changepositions between open and closed positions, and wherein the inputstimulus does not cause the plunger to change a position; taking one ormore voltage measurements across the solenoid in response to the inputstimulus being applied to the solenoid, wherein the voltage of the oneor more voltage measurements are dependent upon the position of theplunger relative to the solenoid in response to the input stimulusapplied to the solenoid; evaluating the one or more voltagemeasurements; and determining whether the plunger is in one of the openand closed positions based on the one or more voltage measurements.

Other embodiments provide one or more computer-readable storage mediumsstoring one or more computer programs configured for use with a computersimulation, the one or more computer programs configured to cause acomputer and/or processor based system to execute steps comprising:causing an input stimulus to be generated and applied to a firstterminal of a solenoid, wherein the solenoid is cooperated with aplunger that is configured to be movable between open and closedpositions in response to a magnetic field generated by the solenoid inresponse to a plunger drive signal causing an opening and closing of anirrigation valve, and wherein the input stimulus does not cause theplunger to change positions and the input stimulus is applied to thesolenoid while the plunger drive signal is not being applied to thesolenoid; causing one or more voltage measurements to be taken across aresistive load cooperated with a second terminal of the solenoid inresponse to the input stimulus; determining a current through theresistive load as a function of the one or more voltage measurements;determining an inductance of the solenoid as a function of thedetermined current and a timing of the input stimulus; evaluating thedetermined inductance relative to a first inductance threshold; anddetermining whether the plunger is in one of the open and closedpositions as a function of a first relationship between the determinedinductance of the solenoid and the first inductance threshold.

Additionally or alternatively, some embodiments provide one or morecomputer-readable storage mediums storing one or more computer programsconfigured for use with a computer simulation, the one or more computerprograms configured to cause a computer and/or processor based system toexecute steps comprising: injecting an input stimulus into a resonantcircuit comprising a solenoid, wherein the solenoid is configured tocooperate with a plunger and to receive a plunger drive signal fromplunger activation circuitry wherein the plunger drive signal configuredto induce a magnetic field relative to the solenoid that causes theplunger to change positions between open and closed positions resultingin opening or closing a valve such that water is allowed to pass throughthe valve when the plunger is in the open position and water isprevented from passing the valve when the plunger is in the closedposition, and wherein the input stimulus will not cause the plunger tomove from a current position and the input stimulus is injected whilethe plunger drive signal is not being applied to the solenoid; whereinthe resonant circuit is configured to be excited by the input stimulusto generate a resonant response that resonates when the plunger is inone of the open position and the closed positions; determining whetherthe resonant response is generated in response to the input stimulus;and determining, through control circuitry, whether the plunger is inone of the open position and closed positions in response to whether theresonant response is generated.

Still further, some embodiments provide one or more computer-readablestorage mediums storing one or more computer programs configured for usewith a computer simulation, the one or more computer programs configuredto cause a computer and/or processor based system to execute stepscomprising: determining, at an irrigation valve control circuitry,whether a voltage on a multi-wire path is less than a first threshold,wherein the irrigation valve control circuitry is coupled with themulti-wire path obtains power from the multi-wire path to open and closean irrigation valve; activating a boost circuitry in response todetermining that the voltage on the multi-wire path is less than thefirst threshold; generating a boost voltage, through the boostcircuitry, that is greater than the voltage on the multi-wire path whenthe voltage on the multi-wire path is less than the first threshold;charging, through the boost voltage, a first charge storage circuitry toa first voltage that is greater than the voltage on the multi-wire pathin response to the boost voltage; and discharging the first chargestorage circuitry to drive a current through a solenoid controllingmovement of a plunger to change positions to one of the open and closedposition, wherein moving the plunger controls the irrigation valve suchthat water is allowed to pass through the valve when the plunger is inan open position and water is prevented from passing the valve when theplunger is in a closed position.

As described above, some embodiments are configured to determine thelocation of the plunger 312. The determination can be performed forsubstantially any reason. In some embodiments, the plunger location canbe confirmed in response to instructions to induce movement of theplunger (i.e., following a plunger drive signal to open or close avalve). Similarly, the plunger location can be determined in response toa status check of a valve or irrigation system, system maintenance,periodically, based on a schedule, a start-up routine, prior toinitiating an irrigation schedule, upon completing an irrigationschedule, as part of a set-up or preset procedure, in response to aninstallation or upgrade to an irrigation system or component of anirrigation system, part of an initialization (e.g., force valves to bein known states prior to initiating an irrigation schedule), or the likeor combinations thereof.

Some embodiments utilize relatively basic circuitry to detect theplunger location. As described above, some embodiments utilize knowninductance value differences between two or more plunger locations. Thisinductance difference is cause by the different plunger positions insidethe coil. The circuitry injects a relatively small input stimulus, whichis too small to provide motive force on the plunger, and one or moremeasurements are taken. For example, voltage measurements across thesolenoid can be determined, voltage across a resistive load can be takenand/or other such measurements can be taken. Based on these one or moremeasurements, the position of the plunger relative to the solenoid canbe determined and/or estimated.

Further, some embodiments utilize resonant circuitry in determining theplunger location relative to the solenoid. For example, through the useof a small amplitude, DC signal induced through an LRC circuitryincluding the solenoid, a response can be measured that is used toindirectly measure the position of the plunger. The location informationcan be used to determine whether the plunger is in a position indicatingthat the valve is open, closed, or in an undetermined position.

Some embodiments additionally or alternatively include boost circuitry.As described above, and depicted in FIG. 1, ICMs 108 can be coupled witha multi-wire path 106 at various locations along the length of themulti-wire path. Typically, the ICMs derive operational power and powerto drive open and close the solenoid valve from a power signal (e.g., anAC waveform) received via the multi-wire path. The length of themulti-wire path, however, may be hundreds of meters or longer. Becauseof relatively long runs of the multi-wire path, the amplitude of the ACwaveform may diminish along the multi-wire path such that the amplitudeis proximate an end of the multi-wire path than proximate the ICI 104,satellite irrigation controller 112 or other source of the AC waveform.Accordingly, at the distal end of the path, the AC power signal mayprovide insufficient power to the ICMs to effectively and/or accuratelyopen or close the solenoid controlled valve. As such, some embodimentsinclude the boost circuitry in the ICM, a separate power circuitrycoupled with the ICM or other such circuitry. The ICM can detect thelevel of the AC signal on the multi-wire path and/or a voltageproportional to the level on the multi-wire path, and activate the boostcircuitry to generate a boosted voltage when the AC signal drops below athreshold. In some embodiments, the boost circuitry includes one or morecharge storage circuitry (e.g., including one or more capacitors,batteries, etc.) to store at least the boosted voltage.

It is noted that in some embodiments, an irrigation control device isprovided that includes boost circuitry and/or plunger detectioncircuitry. For example, while several of the embodiments describedherein indicate that boost circuitry functionality and plunger detectioncircuitry functionality may be implemented in the same device (e.g., seeFIG. 2), it is understood that an irrigation device in some embodimentsmay include boost circuitry without plunger detection circuitry, andthat an irrigation device in some embodiments may include plungerdetection circuitry without boost circuitry.

It is also noted that in some embodiments, an irrigation control deviceincludes boost circuitry and plunger detection circuitry, where theboost circuitry may be any of the boost circuits described herein or anyother boost circuits known in the art, and where the plunger detectioncircuitry may be any of the plunger detection circuits described hereinor any other plunger detection circuits known in the art. Accordingly,in some embodiments, an irrigation control apparatus comprises: chargestorage circuitry electrically coupled with a multi-wire path, whereinthe charge storage circuitry is configured to be charged by a voltage onthe multi-wire path; boost circuitry coupled to the charge storagecircuitry and configured to increase a voltage stored by the chargestorage circuitry when the voltage on the multi-wire path is below athreshold; a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal produced through a discharge of at leastthe charge storage circuitry; and plunger position detection circuitryconfigured to determine whether the plunger is in one of an openposition and a closed position.

Some embodiments provide methods of controlling an irrigation device,comprising: causing an input stimulus to be applied to a solenoid at atime while a plunger drive signal is not being applied to the solenoid,wherein the solenoid is configured to cooperate with a plunger and toreceive the plunger drive signal that induces a magnetic field relativeto the solenoid that causes the plunger to change positions between openand closed positions, and wherein the input stimulus does not cause theplunger to change a position; taking one or more voltage measurementsacross the solenoid in response to the input stimulus being applied tothe solenoid, wherein the voltage of the one or more voltagemeasurements are dependent upon the position of the plunger relative tothe solenoid in response to the input stimulus applied to the solenoid;evaluating the one or more voltage measurements; and determining whetherthe plunger is in one of the open and closed positions based on the oneor more voltage measurements. In some implementations, methods furthercomprise: generating the input stimulus as a tone that oscillates at afixed frequency, wherein the causing the input stimulus to be applied tothe solenoid comprises causing the tone to be applied to the solenoid,wherein the tone does not cause the plunger to change positions.

Other embodiments provide methods of controlling an irrigation device,the methods comprising: causing an input stimulus to be generated andapplied to a first terminal of a solenoid, wherein the solenoid iscooperated with a plunger that is configured to be movable between openand closed positions in response to a magnetic field generated by thesolenoid in response to a plunger drive signal causing an opening andclosing of an irrigation valve, and wherein the input stimulus does notcause the plunger to change positions and the input stimulus is appliedto the solenoid while the plunger drive signal is not being applied tothe solenoid; causing one or more voltage measurements to be takenacross a resistive load cooperated with a second terminal of thesolenoid in response to the input stimulus; determining a currentthrough the resistive load as a function of the one or more voltagemeasurements; determining an inductance of the solenoid as a function ofthe determined current and a timing of the input stimulus; evaluatingthe determined inductance relative to a first inductance threshold; anddetermining whether the plunger is in one of the open and closedpositions as a function of a first relationship between the determinedinductance of the solenoid and the first inductance threshold. In someimplementations, the methods further comprise: activating a resistancecircuitry switch, while at least a portion of the input stimulus isapplied to the solenoid, to direct current passing through the inductor,in response to at least the portion of the input stimulus being appliedto the solenoid, to the resistive load; and wherein the causing the oneor more voltage measurements to be taken comprises causing the one ormore voltage measurements to be taken across the resistive load whilethe current is directed to the resistive load.

Further, some embodiments provide methods of controlling irrigationapparatuses, comprising: injecting an input stimulus into a resonantcircuit comprising a solenoid, wherein the solenoid is configured tocooperate with a plunger and to receive a plunger drive signal fromplunger activation circuitry wherein the plunger drive signal configuredto induce a magnetic field relative to the solenoid that causes theplunger to change positions between open and closed positions resultingin opening or closing a valve such that water is allowed to pass throughthe valve when the plunger is in the open position and water isprevented from passing the valve when the plunger is in the closedposition, and wherein the input stimulus will not cause the plunger tomove from a current position and the input stimulus is injected whilethe plunger drive signal is not being applied to the solenoid; whereinthe resonant circuit is configured to be excited by the input stimulusto generate a resonant response that resonates when the plunger is inone of the open position and the closed positions; determining whetherthe resonant response is generated in response to the input stimulus;and determining, through control circuitry, whether the plunger is inone of the open position and closed positions in response to whether theresonant response is generated.

Some embodiments provide irrigation valve control apparatusescomprising: multiple terminals coupled with a multi-wire path; a firstcharge storage circuitry electrically coupled with at least one of themultiple terminals, wherein the first charge storage circuitry isconfigured to be charged by a voltage on the multi-wire path; a controlcircuitry configured to determine the voltage on the multi-wire path;and a boost circuitry controlled by the control circuitry, wherein thecontrol circuitry in response to determining that the voltage on themulti-wire path is below a threshold activates the boost circuitry toincrease a voltage stored by the first charge storage circuitry.

Further, some embodiments provide methods of controlling irrigationvalves, comprising: determining, at an irrigation valve controlcircuitry, whether a voltage on a multi-wire path is less than a firstthreshold, wherein the irrigation valve control circuitry is coupledwith the multi-wire path obtains power from the multi-wire path to openand close an irrigation valve; activating a boost circuitry in responseto determining that the voltage on the multi-wire path is less than thefirst threshold; generating a boost voltage, through the boostcircuitry, that is greater than the voltage on the multi-wire path whenthe voltage on the multi-wire path is less than the first threshold;charging, through the boost voltage, a first charge storage circuitry toa first voltage that is greater than the voltage on the multi-wire pathin response to the boost voltage; and discharging the first chargestorage circuitry to drive a current through a solenoid controllingmovement of a plunger to change positions to one of the open and closedposition, wherein moving the plunger controls the irrigation valve suchthat water is allowed to pass through the valve when the plunger is inan open position and water is prevented from passing the valve when theplunger is in a closed position.

Some embodiments provide irrigation valve control apparatusescomprising: a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal from plunger activation circuitry whereinthe plunger drive signal is configured to induce a magnetic fieldrelative to the solenoid that causes the plunger to change positionsbetween open and closed positions; an input stimulus source coupled withthe solenoid and configured to apply an input stimulus into the solenoidat a time while the plunger drive signal is not being applied to thesolenoid, wherein the input stimulus is sufficiently small that theinput stimulus applied to the solenoid does not cause the plunger tomove from a current position; sampling circuitry configured to measureone or more voltage measurements corresponding to one or more voltagesacross the solenoid, wherein the one or more voltage measurements aredependent upon the current position of the plunger relative to thesolenoid in response to applying the input stimulus to the solenoid; andcontrol circuitry cooperated with the sampling circuitry to receive theone or more voltage measurements from the sampling circuitry, whereinthe control circuitry is configured to determine whether the plunger isin one of the open and closed positions based on the one or more voltagemeasurements.

Further, some embodiments provide irrigation apparatuses, comprising: asolenoid configured to cooperate with a plunger and to receive a plungerdrive signal from plunger activation circuitry wherein the plunger drivesignal is configured to induce a magnetic field relative to the solenoidthat causes the plunger to change positions between open and closedpositions causing an opening and closing of an irrigation valve; firstswitching circuitry cooperated with the solenoid, wherein the firstswitching circuitry is configured, upon activation, to dictate adirection of electrical current flow through the solenoid, wherein thedirection of current flow while the plunger drive signal is appliedcontrols a direction of movement of the plunger in response to theapplication of the plunger drive signal; an input stimulus sourcecooperated with the solenoid, wherein the input stimulus source isconfigured to generate an input stimulus that is applied to a firstterminal of the solenoid at a time while the plunger drive signal is notbeing applied to the solenoid, and wherein the input stimulus does notcause the plunger to change from a current position; a resistive loadcooperated with a second terminal of the solenoid; sampling circuitrycoupled with the resistive load, wherein the sampling circuitry isconfigured to measure one or more voltage measurements across theresistive load in response to the input stimulus; and control circuitrycoupled with the sampling circuitry, wherein the control circuitry isconfigured to receive the one or more voltage measurements, determine acurrent passing through the resistive load as a function of the one ormore voltage measurements, calculate an estimated inductance of thesolenoid as a function of the determined current and a timing of theinput stimulus, and determine whether the plunger is in one of the openposition and the closed position as a function of the estimatedinductance of the solenoid.

Still other embodiments provide irrigation valve control apparatusescomprising: a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal from plunger activation circuitry whereinthe plunger drive signal is configured to induce a magnetic fieldrelative to the solenoid that causes the plunger to change positionsbetween open and closed positions resulting in opening or closing avalve such that water is allowed to pass through the valve when theplunger is in the open position and water is prevented from passing thevalve when the plunger is in the closed position; control circuitrycooperated with the solenoid and configured to direct the plunger drivesignal into the solenoid to induce movement of the plunger; an inputstimulus source cooperated with the solenoid and configured to apply aninput stimulus into the solenoid at a time while the plunger drivesignal is not being applied to the solenoid, wherein the input stimulusthat is sufficiently small that the input stimulus does not cause theplunger to move from a current position; and a resonant circuitcomprising the solenoid, wherein the resonant circuit is coupled withthe input stimulus source and configured to be excited by the inputstimulus to generate a resonant response that resonates when the plungeris in one of the open position and the closed position; wherein thecontrol circuitry is configured to determine whether the resonantresponse is generated in response to the input stimulus, and todetermine whether the plunger is in one of the open and closed positionsin response to whether the resonant response is generated.

Some embodiments provide irrigation apparatuses, comprising: a solenoidconfigured to cooperate with a plunger and to receive a plunger drivesignal from plunger activation circuitry wherein the plunger drivesignal is configured to induce a magnetic field relative to the solenoidthat causes the plunger to change positions between open and closedpositions causing an opening and closing of an irrigation valve; firstswitching circuitry cooperated with the solenoid, wherein the firstswitching circuitry is configured, upon activation, to dictate adirection of electrical current flow through the solenoid, wherein thedirection of current flow while the plunger drive signal is appliedcontrols a direction of movement of the plunger in response to theapplication of the plunger drive signal; an input stimulus sourcecooperated with the solenoid, wherein the input stimulus source isconfigured to generate an input stimulus that is applied to a firstterminal of the solenoid at a time while the plunger drive signal is notbeing applied to the solenoid, and wherein the input stimulus does notcause the plunger to change from a current position; a resistive loadcooperated with a second terminal of the solenoid; sampling circuitrycoupled with the resistive load, wherein the sampling circuitry isconfigured to measure one or more voltage measurements across theresistive load in response to the input stimulus; and control circuitrycoupled with the sampling circuitry, wherein the control circuitry isconfigured to receive the one or more voltage measurements, determine acurrent passing through the resistive load as a function of the one ormore voltage measurements, calculate an estimated inductance of thesolenoid as a function of the determined current and a timing of theinput stimulus, and determine whether the plunger is in one of the openposition and the closed position as a function of the estimatedinductance of the solenoid. Some embodiments further comprise: theplunger positioned relative to the solenoid, wherein the plunger isconfigured to be movable between the open and closed positions inresponse to the magnetic field generated by the solenoid in response tothe plunger drive signal applied to the solenoid by the plungeractivation circuitry.

Additionally, in some embodiments, the control circuitry, in determiningwhether the plunger is in one of the open and closed positions, isconfigured to evaluate the estimated inductance relative to a firstinductance threshold, and determine whether the plunger is in one of theopen and closed positions as a function of a relationship between theestimated inductance of the solenoid and the first inductance threshold.Further, the control circuitry can be further configured to evaluate theestimated inductance relative to a second inductance threshold, anddetermine whether the plunger is in the other of the open and closedposition as a function of a relationship between the estimatedinductance of the solenoid and the second inductance threshold. In someimplementations the control circuitry is further configured to identifythat the plunger is in an unknown position as the result of therelationship between the estimated inductance of the solenoid and thefirst inductance threshold and the result of the relationship betweenthe estimated inductance of the solenoid and the second inductancethreshold. Furthermore, some embodiments further comprise: secondswitching circuitry cooperated with the solenoid, wherein the secondswitching circuitry is configured, when triggered, to direct currentpassing through the solenoid through the resistive load establishing avoltage across the resistive load; and wherein the control circuitry iscooperated with the second switching circuitry and configured to controlthe second switching circuitry in association with the application ofthe input stimulus. The resistive load can couple between the solenoidand ground when the second switching circuitry is triggered to directthe current passing through the solenoid through the resistive load. Theinput stimulus can comprises a pulse wherein a duration of the pulse isknown to the control circuitry; and wherein the control circuitry, incalculating the estimated inductance, is configured to calculate theestimated inductance as a function of the determined current and thepulse duration. Further, the control circuitry, in some implementations,is configured to calculate an estimated change in current over time as afunction of the known pulse duration and, in calculating the estimatedinductance, calculate the estimated inductance as a function of theestimated change in current over time. Still further, in someembodiments, the sampling circuitry is configured to take at least oneof the one or more voltage measurements at approximately an end of thepulse duration.

In some embodiments, the control circuitry is configured to determinethe position of the plunger without measuring a current. Someembodiments further comprise: a gain stage coupled between the resistiveload and the sampling circuitry, wherein the gain stage is configured toamplify the one or more voltage measurements increasing a dynamic rangeof the sampling circuitry allowing a utilization of a greater number ofbits to digitally represent the sampled one or more voltagemeasurements. In some implementations, the irrigation apparatus furthercomprises: boost circuitry coupled with a multi-wire path comprising atleast two wires, wherein the multi-wire path delivers power; and boostcontrol circuitry configured to determine whether a voltage level on themulti-wire path is below a plunger drive signal threshold and activatesthe boost circuitry; wherein the boost circuitry is configured toenhance a voltage of the plunger drive signal applied to the solenoid toinduce the movement of the plunger to change positions between the openand closed positions. The boost control circuitry, in response todetermining that the voltage level on the multi-wire path is below theplunger drive signal threshold, is further configured, in someembodiments, to generate a pulse width modulated (PWM) signal applied tothe boost circuitry; wherein the boost circuitry is configured togenerate an increased voltage and charge one or more charge storagecircuitry, over a period of time, to a voltage at least equal to theplunger drive signal threshold in response to the PWM signal.

In some embodiments, the control circuitry is further configured toevaluate the one or more voltage measurements relative to a thirdthreshold, and to determine whether the plunger is removed from aposition cooperated with the solenoid as a result of a relationshipbetween the one or more voltage measurements and the third threshold.Additionally, the sampling circuitry, in some embodiments, in measuringthe one or more voltage measurements is configured to take multiplemeasurements over time of the voltage across the resistive load inresponse to the application of the input stimulus. Further, the samplingcircuitry can be configured to take multiple voltage measurementsfollowing the application of the input stimulus; wherein the controlcircuitry is configured to receive the multiple voltage measurements, tocooperate the multiple voltage measurements calculating a cooperativemeasurement; and wherein the control circuitry is configured, whendetermining the current passing through the resistive load, isconfigured to calculate the current passing through the resistive loadas a function of the cooperative measurement.

Some embodiments further comprise: temperature sensing circuitry coupledwith the control circuitry, wherein the temperature sensing circuitry isconfigured to provide an indication of a current temperature of anenvironment in which the solenoid is positioned; and wherein the controlcircuitry, in determining the current passing through the resistive loadas the function of the one or more voltage measurements, is furtherconfigured to adapt the one or more voltage measurements as a functionof the indication of the current temperature. In some implementations,the control circuitry is configured to activate the plunger activationcircuitry to generate the plunger drive signal that is applied to thesolenoid and intended to force the plunger to an intended one of theopen position and the closed position, and to determine whether theplunger is in a stuck condition by determining whether the plunger is inthe intended one of the open position and the closed position after theapplying the plunger drive signal to the solenoid. Further, in someembodiments, the control circuitry, when determining whether the plungeris in one of the open and closed positions, is further configured todetermine one of a level of how open and a level of how closed, whereinthe level of how open and the level of how closed are defined by anestimated proportional position of the plunger relative to a range ofmotion of the plunger and at least one of a fully open position at afirst limit of the range of motion and a fully closed position at asecond limit of the range of motion.

Some embodiments provide irrigation valve control apparatusescomprising: a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal from plunger activation circuitry whereinthe plunger drive signal is configured to induce a magnetic fieldrelative to the solenoid that causes the plunger to change positionsbetween open and closed positions resulting in opening or closing avalve such that water is allowed to pass through the valve when theplunger is in the open position and water is prevented from passing thevalve when the plunger is in the closed position; control circuitrycooperated with the solenoid and configured to direct the plunger drivesignal into the solenoid to induce movement of the plunger; an inputstimulus source cooperated with the solenoid and configured to apply aninput stimulus into the solenoid at a time while the plunger drivesignal is not being applied to the solenoid, wherein the input stimulusthat is sufficiently small that the input stimulus does not cause theplunger to move from a current position; and a resonant circuitcomprising the solenoid, wherein the resonant circuit is coupled withthe input stimulus source and configured to be excited by the inputstimulus to generate a resonant response that resonates when the plungeris in one of the open position and the closed position; wherein thecontrol circuitry is configured to determine whether the resonantresponse is generated in response to the input stimulus, and todetermine whether the plunger is in one of the open and closed positionsin response to whether the resonant response is generated.

The apparatus, in some embodiments, further comprises: the plungerpositioned relative to the solenoid, wherein the plunger is configuredto be movable between the open and closed positions in response to themagnetic field generated by the solenoid in response to the plungerdrive signal applied to the solenoid by the plunger activationcircuitry. Further, in some embodiments, the control circuitry isconfigured to determine a voltage amplitude of a response generated bythe resonant circuit in response to the input stimulus; and wherein thecontrol circuitry in determining whether the resonant response isgenerated is configured to compare peak voltage to a voltage threshold,and to determine whether the resonant response is generated based on adetermined relationship between the peak voltage and the voltagethreshold. Some embodiments further comprise: sampling circuitryconfigured to measure one or more voltage measurements corresponding toone or more voltages across the solenoid, wherein the one or morevoltage measurements are dependent upon the current position of theplunger relative to the solenoid in response to the input stimulusapplied to the solenoid, wherein the control circuitry is furtherconfigured to evaluate the one or more voltage measurements relative toa second threshold, and determine whether the plunger is in one of theopen position and the closed position as a function of a secondrelationship between the one or more voltage measurements and the secondthreshold.

Additionally, in some embodiments, the control circuitry is furtherconfigured to identify that the plunger is in an unknown position as theresult of the determined relationship between the peak voltage and thevoltage threshold and the second relationship between the one or morevoltage measurements and the second threshold. In some implementations,the input stimulus source is further configured to apply an alternateinput stimulus into the solenoid; wherein the control circuitry isconfigured to determine whether the resonant response is generated inresponse to the alternate input stimulus, and to determine whether theplunger is removed from a position cooperated with the solenoid inresponse to whether the resonant response is generated based on thealternate input stimulus. Some apparatus, in accordance with someembodiments, further comprise: sampling circuitry configured to takemultiple voltage measurement over time of the voltage across thesolenoid in response the application of the input stimulus to theresonant circuit; wherein the control circuitry, in determining whetherthe resonant response is generated in response to the input stimulus, isconfigured to evaluate the multiple voltage measurements. The samplingcircuitry, in some embodiments, is coupled with the solenoid to take themultiple voltage measurements across the solenoid. Further, in someembodiments the input stimulus comprises a single square pulse signal.In other embodiments, the input stimulus comprises a sine wave signal.In yet other embodiments, the input stimulus comprises a periodic squarewave signal.

Some embodiments further comprise: sampling circuitry configured tomeasure one or more voltage measurements corresponding to one or morevoltages across the solenoid, wherein the one or more voltagemeasurements are dependent upon the current position of the plungerrelative to the solenoid in response to the input stimulus applied tothe solenoid, wherein the control circuitry is further configured toevaluate the one or more voltage measurements in determining whether theresonant response is generated in response to the input stimulus;wherein the sampling circuitry in taking each of the one or more voltagemeasurements is configured to take the one or more voltage measurementsafter a predefined period of time following the input stimulus beingapplied to the solenoid. Additionally or alternatively, some embodimentsfurther comprise: a gain stage coupled between the solenoid and asampling circuitry, wherein the gain stage is configured to amplify,prior to taking one or more voltage measurements, the response inducedby the resonant circuit producing an amplified response corresponding tovoltage across the solenoid; and wherein the sampling circuitry inmeasuring one or more voltage measurements is configured to measure theone or more voltage measurements of the amplified response correspondingto the voltage across the solenoid with a resulting increased dynamicrange of the sampling circuitry allowing the utilization of a greaternumber of bits to digitally represent the sampled signal than availablewithout the gain stage. Some embodiments further comprise samplingcircuitry configured to take multiple voltage measurements following theapplication of the input stimulus; wherein the control circuitry isconfigured to receive the multiple voltage measurements, to cooperatethe multiple voltage measurements calculating a cooperative measurement;and wherein the control circuitry is configured, when determiningwhether the resonant response is generated, to evaluate the cooperativemeasurement relative to a first threshold, and determine whether theresonant response is generated as a result of a relationship between thecooperative measurement and the first threshold.

In some implementations, an apparatus further comprises: boost circuitrycoupled with a multi-wire path that delivers power; and boost controlcircuitry configured to determine whether a voltage level on themulti-wire path is below a plunger drive signal threshold and activatesthe boost circuitry; wherein the boost circuitry is configured toincrease a voltage of the plunger drive signal applied to the solenoidto induce the movement of the plunger to change positions between theopen and closed positions. Further, in some embodiments, the boostcontrol circuitry, in response to determining that the voltage level onthe multi-wire path is below the plunger drive signal threshold, isfurther configured to generate a pulse width modulated (PWM) signalapplied to the boost circuitry; wherein the boost circuitry isconfigured to generate an increased voltage and charge one or morecharge storage circuitry, over a period of time, to a voltage at leastequal to the plunger drive signal threshold in response to the PWMsignal.

Some embodiments further comprise: temperature sensing circuitry coupledwith the control circuitry, wherein the temperature sensing circuitry isconfigured to provide an indication of a current temperature of anenvironment in which the solenoid is positioned; and wherein the controlcircuitry in determining whether the resonant response is generated isfurther configured to adapt one or more voltage measurements, which aredependent upon the position of the plunger relative to the solenoid, asa function of the indication of the current temperature. The controlcircuitry, in some embodiments, is configured to activate the plungeractivation circuitry to generate the plunger drive signal that isapplied to the solenoid and intended to force the plunger to an intendedone of the closed position and the open position, and to determinewhether the plunger is in a stuck condition by determining whether theplunger is in the intended one of the open position and the closedposition after the applying the plunger drive signal to the solenoid.Further, in some implementations, the control circuitry is configured toidentify that the plunger is in one of the open and closed positions inresponse to determining that the resonant response is not detected andto identify that the plunger is in the other of the open and closedposition when the resonant response is detected. Additionally oralternatively, in some embodiments the control circuitry, whendetermining whether the plunger is in one of the open and closedpositions, is further configured to determine one of a level of how openand a level of how closed, wherein the level of how open and the levelof how closed are defined by an estimated proportional position of theplunger relative to a range of motion of the plunger and at least one ofa fully open position at a first limit of the range of motion and afully closed position at a second limit of the range of motion.

Some embodiments provide irrigation control apparatuses comprising: afirst charge storage circuitry electrically coupled with a multi-wirepath, wherein the first charge storage circuitry is configured to becharged by a voltage on the multi-wire path; control circuitryconfigured to determine the voltage on the multi-wire path; boostcircuitry controlled by the control circuitry, wherein the controlcircuitry in response to determining that the voltage on the multi-wirepath is below a threshold activates the boost circuitry to increase avoltage stored by the first charge storage circuitry; a solenoidconfigured to cooperate with a plunger and to receive a plunger drivesignal produced through a discharge of at least the first charge storagecircuitry; and plunger position detection circuitry configured to applyan input stimulus into the solenoid and to determine whether the plungeris in one of an open position and a closed position in response toapplying the input stimulus.

While the invention herein disclosed has been described by means ofspecific embodiments, examples and applications thereof, numerousmodifications and variations could be made thereto by those skilled inthe art without departing from the scope of the invention set forth inthe claims.

What is claimed is:
 1. An irrigation valve control apparatus comprising:a solenoid configured to cooperate with a plunger and to receive aplunger drive signal from plunger activation circuitry, wherein theplunger drive signal is configured to induce a magnetic field relativeto the solenoid that causes the plunger to change positions between openand closed positions; an input stimulus source coupled with the solenoidand configured to apply an input stimulus into the solenoid at a timewhile the plunger drive signal is not being applied to the solenoid,wherein the input stimulus is sufficiently small that the input stimulusapplied to the solenoid does not cause the plunger to move from acurrent position; sampling circuitry configured to measure one or morevoltage measurements corresponding to one or more voltages across thesolenoid, wherein the one or more voltage measurements are dependentupon the current position of the plunger relative to the solenoid inresponse to applying the input stimulus to the solenoid; and controlcircuitry cooperated with the sampling circuitry to receive the one ormore voltage measurements from the sampling circuitry, wherein thecontrol circuitry is configured to determine whether the plunger is inone of the open and closed positions based on the one or more voltagemeasurements.
 2. The apparatus of claim 1, further comprising: theplunger positioned relative to the solenoid, wherein the plunger isconfigured to be movable between the open and closed positions inresponse to the magnetic field generated by the solenoid in response tothe plunger drive signal applied to the solenoid by the plungeractivation circuitry.
 3. The apparatus of claim 1, wherein the controlcircuitry, in determining whether the plunger is in one of the open andclosed positions, is configured to evaluate the one or more voltagemeasurements relative to a first threshold and determine whether theplunger is in one of the open and closed positions as a result of arelationship between the one or more voltage measurements and the firstthreshold.
 4. The apparatus of claim 3, wherein the control circuitry isfurther configured to evaluate the one or more voltage measurementsrelative to a second threshold, and determine whether the plunger is inthe other of the open and closed positions as a function of a secondrelationship between the one or more voltage measurements and the secondthreshold.
 5. The apparatus of claim 4, wherein the control circuitry isfurther configured to identify that the plunger is in an unknownposition as the result of the first relationship between the one or morevoltage measurements and the first threshold and the second relationshipbetween the one or more voltage measurements and the second threshold.6. The apparatus of claim 1, wherein the control circuitry is furtherconfigured to evaluate the one or more voltage measurements relative toa third threshold, and to determine whether the plunger is removed froma position cooperated with the solenoid as a result of a relationshipbetween the one or more voltage measurements and the third threshold. 7.The apparatus of claim 1, further comprising: a resistance-capacitancecircuit (RC circuit) coupled with the solenoid at a first terminal ofthe solenoid forming an inductance, resistance and capacitance circuit(LRC circuit), wherein the RC circuit comprises a first resistor and afirst capacitor cooperatively coupled with the solenoid.
 8. Theapparatus of claim 7, wherein the sampling circuitry in taking each ofthe one or more voltage measurements is configured to take multiplemeasurements over time of the voltage across the solenoid in response tothe application of the input stimulus to the LRC circuit.
 9. Theapparatus of claim 7, wherein the sampling circuitry is coupled with thesolenoid at a connection between the first terminal of the solenoid andthe RC circuit.
 10. The apparatus of claim 1, wherein the plungeractivation circuitry is distinct from the sampling circuitry and thecontrol circuitry.
 11. The apparatus of claim 1, wherein the inputstimulus comprises at least one of a sine wave signal, a periodic squarewave signal, and a single square pulse signal.
 12. The apparatus ofclaim 1, wherein the plunger drive signal is distinct from the inputstimulus source.
 13. The apparatus of claim 1, wherein the samplingcircuitry in taking each of the one or more voltage measurements isconfigured to take the one or more voltage measurements after apredefined period of time following the input stimulus being applied tothe solenoid.
 14. The apparatus of claim 1, further comprising: a gainstage coupled between the solenoid and the sampling circuitry, whereinthe gain stage is configured to amplify, prior to taking the one or morevoltage measurements, an amplitude-modulated pulse induced at least inpart by the solenoid in response to the input stimulus producing anamplified, amplitude-modulated pulse corresponding to voltage across thesolenoid; and wherein the sampling circuitry in measuring the one ormore voltage measurements is configured to measure the one or morevoltage measurements of the amplified, amplitude-modulated pulsecorresponding to the voltage across the solenoid with a resultingincreased dynamic range of the sampling circuitry allowing theutilization of a greater number of bits to digitally represent thesampled signal than available without the gain stage.
 15. The apparatusof claim 1, wherein the sampling circuitry is configured to takemultiple voltage measurements following the application of the inputstimulus; wherein the control circuitry is configured to receive themultiple voltage measurements, to cooperate the multiple voltagemeasurements calculating a cooperative measurement; and wherein thecontrol circuitry is configured, when evaluating the one or more voltagemeasurements, to evaluate the cooperative measurement relative to afirst threshold, and determine whether the plunger is in one of theclosed position and the open position as a result of a relationshipbetween the cooperative measurement and the first threshold.
 16. Theapparatus of claim 1, further comprising: boost circuitry coupled with amulti-wire path comprising at least two wires, wherein the multi-wirepath delivers power; and boost control circuitry configured to determinewhether a voltage level on the multi-wire path is below a plunger drivesignal threshold and activates the boost circuitry; wherein the boostcircuitry is configured to increase a voltage of the plunger drivesignal applied to the solenoid to induce the movement of the plunger tochange positions between the open and closed positions.
 17. Theapparatus of claim 16, wherein the boost control circuitry, in responseto determining that the voltage level on the multi-wire path is belowthe plunger drive signal threshold, is further configured to generate apulse width modulated (PWM) signal applied to the boost circuitry;wherein the boost circuitry is configured to generate an increasedvoltage and charge one or more charge storage circuitry, over a periodof time, to a voltage at least equal to the plunger drive signalthreshold in response to the PWM signal.
 18. The apparatus of claim 1,further comprising: temperature sensing circuitry coupled with thecontrol circuitry, wherein the temperature sensing circuitry isconfigured to provide an indication of a current temperature of anenvironment in which the solenoid is positioned; and wherein the controlcircuitry in evaluating the one or more voltage measurements is furtherconfigured to adapt the evaluation of the one or more voltagemeasurements, which are dependent upon the position of the plungerrelative to the solenoid, as a function of the indication of the currenttemperature.
 19. The apparatus of claim 1, wherein the control circuitryis configured to activate the plunger activation circuitry to generatethe plunger drive signal that is applied to the solenoid and intended toforce the plunger to an intended one of the closed position and the openposition, and to determine whether the plunger is in a stuck conditionby determining whether the plunger is in the intended one of the openposition and the closed position after the applying the plunger drivesignal to the solenoid.
 20. The apparatus of claim 1, wherein thecontrol circuitry, when determining whether the plunger is in one of theopen and closed positions, is further configured to determine one of alevel of how open and a level of how closed, wherein the level of howopen and the level of how closed are defined by an estimatedproportional position of the plunger relative to a range of motion ofthe plunger and at least one of a fully open position at a first limitof the range of motion and a fully closed position at a second limit ofthe range of motion.
 21. The apparatus of claim 1, wherein the controlcircuitry, when determining whether the plunger is in one of the openand closed positions, is further configured to determine a proportionallocation of the plunger relative to one of the open and closed positionsand a range of motion of the plunger.
 22. An irrigation apparatus,comprising: a solenoid configured to cooperate with a plunger and toreceive a plunger drive signal from plunger activation circuitry whereinthe plunger drive signal is configured to induce a magnetic fieldrelative to the solenoid that causes the plunger to change positionsbetween open and closed positions causing an opening and closing of anirrigation valve; first switching circuitry cooperated with thesolenoid, wherein the first switching circuitry is configured, uponactivation, to dictate a direction of electrical current flow throughthe solenoid, wherein the direction of current flow while the plungerdrive signal is applied controls a direction of movement of the plungerin response to the application of the plunger drive signal; an inputstimulus source cooperated with the solenoid, wherein the input stimulussource is configured to generate an input stimulus that is applied to afirst terminal of the solenoid at a time while the plunger drive signalis not being applied to the solenoid, and wherein the input stimulusdoes not cause the plunger to change from a current position; aresistive load cooperated with a second terminal of the solenoid;sampling circuitry coupled with the resistive load, wherein the samplingcircuitry is configured to measure one or more voltage measurementsacross the resistive load in response to the input stimulus; and controlcircuitry coupled with the sampling circuitry, wherein the controlcircuitry is configured to receive the one or more voltage measurements,determine a current passing through the resistive load as a function ofthe one or more voltage measurements, calculate an estimated inductanceof the solenoid as a function of the determined current and a timing ofthe input stimulus, and determine whether the plunger is in one of theopen position and the closed position as a function of the estimatedinductance of the solenoid.